atrocious service

The service I received at home choice is disgusting and appalling and down right disappointing I had paid up my account on the 02/08/18 which was more than what was required and called in on the 07/08/18 to get the account closed and also requested for a paid up letter in which I received immediately to my horror I received a statement from them on the 12/09/18 informing that they are charging me interest on a paid up account and paid up I mean I have paid more so my closed off account is on a negative balance of R27,35.