no use complaining

I received an incorrect account after paying ahead of time more then my installment required which I repeatedly told cashier she wasn't performing my payment as I requested, when I queried I was promised to be contacted and issue to be rectified. To date, I'm yet to be contacted, I have received repeated incorrect bills, including interest and other costs. Despite the assurance of a store manager, and his effort to rectify it, my account remains incorrect, and I'm strongly considering closing my account. HIGHLY IRRITATED AND DISGUSTED BY THE SERVICE...