False accusations

I opened an account at Ackermans three months ago. I have been paying it every since and I haven't skipped a payment. I asked them if they can debit it monthly they said it's not a great idea coz they will forget to debit and mess up my credit record. We agreed that I pay monthly cash. So I was trying to apply and buy a car so the car dealer can't help me because Ackermans said I missed a payment and I never did miss a payment since I opened an account with them. Can they clear my credit record coz they really messing up with my credit record I can't apply for anything because of them.