If a customer makes a payment by mistake, pays too much, or wishes to return an item, can I refund the customer's money?

Yes, you can refund transactions through SecurePay. Multiple refunds may be performed on a transaction if the total refunded amount does not exceed the total of the original payment. Refunds are performed through the Merchant Login facility. 

Merchants can only refund a payment back to the card used for the original payment.

Find the reference id, date and time of payment from the Edit Booking - Payments tab on the timesheet of the booking or in mitournament from the payments screen