Unauthorized debiting for settled account

I had a personal loan with you guys and requested a settlement letter I subsequently closed off the account same day letter was received.i called and the aknowledged that I had paid and will receive a paid up letter. Now two months later I have resumed the debit orders.u are basically *****ing my money as it’s an now an unauthorized debit order.let me know when u will refund my money ASAP or I will escalate this theft to the banking ombudsman