How to refund a customer whose balance is in credit due to invoice overpayment

How to refund a customer whose balance is in credit due to invoice overpayment

I have a customer whose account balance is in credit by a small amount due to an invoice overpayment.

I understand how to issue a refund by raising a credit note but the account is already in credit so this scenario is a little different. Please can you offer some guidance on how to record the transaction? I would like to issue the refund by bank transfer if this is relevant.

Simon