The only action available for a MerchantTrack transaction record on the SOS Pay list is Refund, which is also available as a batch action. The SOS Pay list is accessible via the SOS Pay link in the upper right corner of the Payments list (Operations > Sales > Payments)
When the Refund button is selected, a pop-up window will appear with an Amount field. Indicate the amount you wish to refund, then select Submit. The refund will be processed in MerchantTrack immediately, then added to the SOS Pay list with Refunded or Partial refund indicated in the transaction record’s Status column.

Refunds may involve additional actions on your part, depending on the situation. Refer to the subsections below for more information.
If an error was made on a payment transaction that resulted in an incorrect charge amount in MerchantTrack, locate the transaction on the SOS Pay list and issue a refund. Then locate the payment transaction on the Payments list (Operations > Sales > Payments) and delete that transaction.
You can then generate a new payment transaction from the invoice with the correct amount, which, upon saving, will result in processing the correct payment in MerchantTrack.
If a customer cancels an order, process a refund in MerchantTrack for the full amount. It gives the money back to your customer. A refund of the payment in SOS Inventory does not affect QuickBooks Online. It is not necessary to delete the payment transaction from the Payments list in SOS Inventory. However, if you delete the payment for a canceled order, you may wish to also delete the invoice associated with that payment—or void the invoice in QuickBooks Online.