Fidel now offers refund transaction matching. If a transaction refund is made at the same location for the same amount as the original transaction, Fidel will match the two transactions.
The original transaction will gain a new field refundTransactionId that points to the refund transaction.
The refund transaction will point to the original transaction with the originalTransactionId field.
Read more here: https://fidel.uk/docs/transactions/#refund-transactions