Create Refund

To guarantee safe retries, the merchant should offer their refund ID or reference, aligning with their internal records Unique values for the `requestID` and `merchantReference` are required to guarantee safe retries. It is recommended that the merchant generates a UUID for each unique refund request. The `refundMerchantReference` is a unique reference that when provided, will appear in the daily settlement file as "Payment Event Id". In most cases, this would hold the same value as the `merchantReference`.