If you would like to confirm that you have been re-paid a debt, here is a sample template you can use to write a letter acknowledging payment of debt.
To [Recipient name]
Dear, [Recipient name]
This letter is to inform you that [Name of company] has received the outstanding amount of [Amount] owed by you on [Date]. It was sent by bank account number [Number] to our bank account number [Number]. It was received [Number] of days after the initial payment. We appreciate the fulfillment of the rest of the amount.
We request you to pay the complete amount at the earliest during future transactions as prompt payment will be appreciated. We are grateful for your business and hope to continue providing our services in the future.
[Name of company]