Debit order - not authorised

At first I was very happy. I paid my first debit order before the due date, but the debit order went through my account. I phoned and the lady said if its between 5 days from the debit order date it will go through. I send the debit order back. The next month I paid on the 23rd, its more than 7 days before the debit order date. The debit order went through again, I send it back. End of August, I decide to let the debit order go through, It went through double? I send it back and paid my instalment myself. Yesterday I receive a FINAL NOTICE, because after numerous attemps to collect the outstanding amounts from my account have failed. Before my account falls further behind? My account is paid up to date, I really am very upset. Ive got all my POP, I did send it through to their email address, but no answer yet. I need to see my statement to see whats going on. I did ask for a statement but havent received anything yet.