First of all, the payment should be refunded the same way it was charged. Therefore, the first step in the refunding process would be to define if it was the cash, terminal, or Merchant (online payment gateway/Merchant terminal) payment.
How the payment was charged?
As payments are connected to the guest profile, not the reservation, please navigate to the guest's payment section.
First payment for 8 EUR is a Cash payment, we can see it in the first column "Type", also you can see the column Cashier is filled in.
The second payment for 100 EUR is a PDQ Terminal payment, as there is no Identifier in the second column - this is not the Merchant Terminal payment.
The third payment for 220.36 EUR is a payment that was done via Merchant, as each of those has an unique identifier assigned so we can track the transaction.
Please, note, that Adyen identifier looks a bit different, 16 number in a row, for example "1234567899999999".
How to refund the guest?
If you have refunded the guest via your PDQ Terminal, by wire transfer ( External payment) or in Cash, and need to note in the system, you can do it in the billing screen of the guest:
How to refund a Cash payment?
How to refund a PDQ Terminal payment?
How to refund a Merchant payment?