Debit Order - Vehicle Asset Finance

Over the past 8 months more or less my vehicle payments do not go through via debit order as normaly would,there is always more than enough funds in my account for the payments to go off without a problem. I have to phone every single month and go through the whole security check process and tell them to do it manually. I’ve been to the bank myself and nobody seems to get the problem sorted over there nor at the call center. Please advise what steps I should follow now to get you to do your job properly. My fantastic credit rating is most likely taking a dive because of your incompetence