repossession threats after payment made

In October we financed a car through absa bank, with first payment due NOV. nov instalment doesn't come off so when we queried why, they had the wrong banking details. it was corrected and we asked the instalment be taken off. it wasn't. so December instalment comes off with no issue and now we are being threatened that if we don't pay the arrears - THEY HAD THE WRONG DETAILS AND WE ASKED THEM TO DEBIT- how can this be? we spoke to a guy named Tobogo who had sorted this out and sent us a new \contract"from dec instead of Nov and now Viv wont accept it and is threatening to hand over to legal! why? this will be the LAST time we ever use absa bank and ill make sure I let everyone know how pathetically useless and bully like they are! after their mistake"