diff --git a/projects/plugins/crm/changelog/revert-34211-fix-crm-invoice-total-credit-refund b/projects/plugins/crm/changelog/revert-34211-fix-crm-invoice-total-credit-refund
new file mode 100644
index 0000000000000..08b0593520925
--- /dev/null
+++ b/projects/plugins/crm/changelog/revert-34211-fix-crm-invoice-total-credit-refund
@@ -0,0 +1,4 @@
+Significance: patch
+Type: changed
+
+Invoices: Changing total amount calculation in preview and pdf when refunds or credit notes are applied, back to pre 6.4.0 implementation.
diff --git a/projects/plugins/crm/includes/ZeroBSCRM.DAL3.Obj.Invoices.php b/projects/plugins/crm/includes/ZeroBSCRM.DAL3.Obj.Invoices.php
index b21784bd2a7d9..ed00153274981 100644
--- a/projects/plugins/crm/includes/ZeroBSCRM.DAL3.Obj.Invoices.php
+++ b/projects/plugins/crm/includes/ZeroBSCRM.DAL3.Obj.Invoices.php
@@ -2752,52 +2752,58 @@ public function getOutstandingBalance($invoiceID=-1){
             if (is_array($invoice)){
 
                 // get total due
-                $invoiceTotalValue = 0.0; if (isset($invoice['total'])) $invoiceTotalValue = (float)$invoice['total'];
+						$invoice_total_value = 0.0;
+						if ( isset( $invoice['total'] ) ) {
+							$invoice_total_value = (float) $invoice['total'];
+							// this one'll be a rolling sum
+							$transactions_total_value = 0.0;
 
-						// this one'll be a rolling sum
-						$transactions_total_value = 0.0;
+							// cycle through trans + calc existing balance
+							if ( isset( $invoice['transactions'] ) && is_array( $invoice['transactions'] ) ) {
 
-						// cycle through trans + calc existing balance
-						if ( isset( $invoice['transactions'] ) && is_array( $invoice['transactions'] ) ) {
+								// got trans
+								foreach ( $invoice['transactions'] as $transaction ) {
 
-							// got trans
-							foreach ( $invoice['transactions'] as $transaction ) {
+									// should we also check for status=completed/succeeded? (leaving for now, will let check all):
 
-								// should we also check for status=completed/succeeded? (leaving for now, will let check all):
+									// get amount
+									$transaction_amount = 0.0;
 
-								// get amount
-								$transaction_amount = 0.0;
+									if ( isset( $transaction['total'] ) ) {
+										$transaction_amount = (float) $transaction['total'];
 
-								if ( isset( $transaction['total'] ) ) {
-									$transaction_amount = (float) $transaction['total'];
-								}
+										if ( $transaction_amount > 0 ) {
+
+											switch ( $transaction['type'] ) {
+												case __( 'Sale', 'zero-bs-crm' ):
+													// these count as debits against invoice.
+													$transactions_total_value -= $transaction_amount;
 
-								switch ( $transaction['type'] ) {
+													break;
 
-									case __( 'Sale', 'zero-bs-crm' ):
-										// these count as debits against invoice.
-										$transactions_total_value -= $transaction_amount;
+												case __( 'Refund', 'zero-bs-crm' ):
+												case __( 'Credit Note', 'zero-bs-crm' ):
+													// these count as credits against invoice.
+													$transactions_total_value += $transaction_amount;
 
-										break;
+													break;
 
-									case __( 'Refund', 'zero-bs-crm' ):
-									case __( 'Credit Note', 'zero-bs-crm' ):
-										// These count as credits against invoice, and should be added.
-										$transactions_total_value -= abs( (float) $transaction_amount );
+											} // / switch on type (sale/refund)
 
-										break;
+										} // / if trans > 0
 
-								} // / switch on type (sale/refund)
+									} // / if isset
 
-							} // / each trans
+								} // / each trans
 
-							// should now have $transactionsTotalValue & $invoiceTotalValue
-							// ... so we sum + return.
-							return $invoiceTotalValue + $transactions_total_value; // phpcs:ignore WordPress.NamingConventions.ValidVariableName.VariableNotSnakeCase
+								// should now have $transactions_total_value & $invoice_total_value
+								// ... so we sum + return.
+								return $invoice_total_value + $transactions_total_value;
 
-						} // / if has trans
+							} // / if has trans
+						} //  if isset invoice total
 
-            } // / if retrieved inv
+					} // / if retrieved inv
 
         } // / if invoice_id > 0
 
diff --git a/projects/plugins/crm/includes/ZeroBSCRM.InvoiceBuilder.php b/projects/plugins/crm/includes/ZeroBSCRM.InvoiceBuilder.php
index 48c0592b6b854..0ea17c091872b 100644
--- a/projects/plugins/crm/includes/ZeroBSCRM.InvoiceBuilder.php
+++ b/projects/plugins/crm/includes/ZeroBSCRM.InvoiceBuilder.php
@@ -621,22 +621,23 @@ function zeroBSCRM_invoicing_generateStatementHTML_v3( $contact_id = -1, $return
 
 						// ignore if status_bool (non-completed status)
 						$partial['status_bool'] = (int) $partial['status_bool'];
-						if ( isset( $partial ) && $partial['status_bool'] == 1 && isset( $partial['total'] ) ) { // phpcs:ignore Universal.Operators.StrictComparisons.LooseEqual
-
-							switch ( $partial['type'] ) {
-								case __( 'Sale', 'zero-bs-crm' ):
-									// these count as debits against invoice.
-									$balance   = $balance - $partial['total'];
-									$payments += $partial['total'];
-
-									break;
-								case __( 'Refund', 'zero-bs-crm' ):
-								case __( 'Credit Note', 'zero-bs-crm' ):
-									// These count as credits against invoice, and should be added.
-									$balance  -= abs( (float) $partial['total'] );
-									$payments -= abs( (float) $partial['total'] );
-
-									break;
+						if ( isset( $partial ) && $partial['status_bool'] == 1 && isset( $partial['total'] ) && $partial['total'] > 0 ) { // phpcs:ignore Universal.Operators.StrictComparisons.LooseEqual
+
+							// v3.0+ has + or - partials. Account for that:
+							if ( $partial['type_accounting'] === 'credit' ) {
+
+								// credit note, or refund
+								$balance = $balance + $partial['total'];
+								// add to payments
+								$payments += $partial['total'];
+
+							} else {
+
+								// assume debit
+								$balance = $balance - $partial['total'];
+
+								// add to payments
+								$payments += $partial['total'];
 							}
 						}
 					} // /foreach
@@ -1085,20 +1086,14 @@ function zeroBSCRM_invoicing_generateInvoiceHTML( $invoice_id = -1, $template =
 			// ignore if status_bool (non-completed status)
 			$partial['status_bool'] = (int) $partial['status_bool'];
 			if ( isset( $partial ) && $partial['status_bool'] == 1 ) { // phpcs:ignore Universal.Operators.StrictComparisons.LooseEqual
-				// v3.0+ has + or - partials. Account for that.
-				switch ( $partial['type'] ) {
-
-					case __( 'Sale', 'zero-bs-crm' ):
-						// these count as debits against invoice.
-						$balance = $balance - $partial['total'];
-						break;
-
-					case __( 'Refund', 'zero-bs-crm' ):
-					case __( 'Credit Note', 'zero-bs-crm' ):
-						// These count as credits against invoice, and should be added.
-						$balance -= abs( (float) $partial['total'] );
-						break;
 
+				// v3.0+ has + or - partials. Account for that:
+				if ( $partial['type_accounting'] === 'credit' ) {
+					// credit note, or refund
+					$balance = $balance + $partial['total'];
+				} else {
+					// assume debit
+					$balance = $balance - $partial['total'];
 				}
 
 				$partials_table .= '<tr class="total-top">';
diff --git a/projects/plugins/crm/js/ZeroBSCRM.admin.invoicebuilder.js b/projects/plugins/crm/js/ZeroBSCRM.admin.invoicebuilder.js
index 2f8c5461cf38b..0a57d09869866 100644
--- a/projects/plugins/crm/js/ZeroBSCRM.admin.invoicebuilder.js
+++ b/projects/plugins/crm/js/ZeroBSCRM.admin.invoicebuilder.js
@@ -1569,10 +1569,8 @@ function zbscrm_JS_calc_amount_due() {
 			// get
 			var v = jQuery( '.zbs-partial-value', ele ).text();
 
-			var label = jQuery( '.zlabel', ele ).text();
-
 			// detect +-
-			var multiplier = 1; // gets turned to -1 if negative ()
+			var multiplier = 1; // gets turned to -1 if negotive ()
 
 			// got -?
 			if ( v.includes( '(' ) ) {
@@ -1581,11 +1579,10 @@ function zbscrm_JS_calc_amount_due() {
 			}
 			v = parseFloat( v ) * multiplier;
 
-			if (  label.includes( 'Refund' ) || label.includes( 'Credit' ) ) {
-				amount_due -= Math.abs( v );
-			} else {
-				amount_due -= v;
-			}
+			// debug console.log('amount:',[jQuery('.zbs-partial-value',ele).text(),amount_due,v]);
+
+			// do it :)
+			amount_due -= v;
 		} );
 
 		jQuery( '#inv-amount-due' ).html( amount_due.toFixed( zbs_root.currencyOptions.noOfDecimals ) );