Payment not reflected on system

I bought a couch and 2 occasional chairs from Rochester Northgate beginning of October 2017. The couches were to be paid off over 3 months. When I went to make my second payment, the sales person Grace, made an error on the system which caused me to pay twice. That was fine because that meant I have paid off my goods earlier than requested. I am now told that due to the error, they are unable to update my account to reflect the amounts paid so that my goods could be delivered. I was promised by the store manager that this will be corrected by their accounts department. This was on the 24th November . Todate this has still not been corrected. The manager Keith , keeps promising to call me, but doesn’t. I went to the store yesterday, to my surprise my account shows that I now owe R18000. My total purchase was for R16000, I paid R15000. I have gone to the store numerous times to try pay the balance of R1000 that is outstanding, but I haven’t been able to, due to this error . I am appalled by the service I received from this store , especially from Keith, as he always make promises, and is always complaining about his store problems that have nothing to do with me as a customer. At this point I either want my money back or my goods delivered before Christmas. I have never bought anything from Rochester, and I regret, their service is very disappointing for such a big store!