Credit Profile impacted due to incompetence

I purchased goods via Game Finance in 05/15, then there have been endless issues with not only the delivery channel (Game City) but the finance structure. I requested a 12 month payment period and when my installment was not deducted correctly (a lesser amount). I immediately called RCS/Game Finance division to enquire. I was advised that I had agreed to a 60 month payment period. I disagreed with this and asked management to listen to the call, Margmarie agreed that this was an incorrect data capture and was in fact a 12 month period. I called on the 26/05/15 and have not received any feedback since. The only time when I receive feedback is when I call the Call Centre and request to speak to Margmarie, who at that time advises me that she is awaiting approval of a process to rectify the matter. During the past 4 months I have had my credit profile impacted, as a business owner I cannot explain to another financial institution why I need to finance R12 000 over 5 years? If Game/RCS cannot put in place a process then please cancel the account and write off the amount. If I have to incur financial loss then surely you should too. This contract should be void due to breach of contract