Refund request for double payment

I paid my account on 25 January via the app, however on 27 January I noticed that a debit order had gone off my account as well, thereby making it a double payment. I called RCS to request a refund as I was not made aware of the debit order and was simply told its in the terms and conditions. Well that's all good ans well, the staff member who helped with with the collection of my card told me I could pay on the app or in store, didn't mention anything about a debit order. Well it's been over a week since my refund request and I have heard nothing. Please refund me the double payment.