Never admit to their fault, but blame the customer

i took a 24 month contract with Altech autopage, According to the contract i signed, it clearly states that my account is with STANDARD BANK , and payment method was a debit order,BUT they had other ideas, instead they set it to another customer who dealt with NEDBANK, so the problem was resolved(SO I THOUGHT) as i was willing to pay back the money over the remainder of my contract, NOW THEY ARE DEMANDING THE MONEY FROM ME(+- R3500) WITH IMMEDIATE EFFECT, and even listed me with a negative rating on CREDIT BUREAU, when it was their error, But still refusing to admit it, and blaming the customer.<br> i've even spoken to the supervisor and nothing was done