Poor Service costing me money!!!!

I signed up for the 20GB on a 4MB line service for R499 (which includes ADSL and voice line rental, and excludes voice usage) at the Century City Telkom store in Cape Town. First they capture my address incorrectly resulting in a 2 week delay with the installation of the lines at my premises, I had to go in store to correct this. Then they tell me they incorrectly captured my order as 100GB!!! They 'correct' it, and I head home. I check the online service portal, they incorrectly 'corrected' my order and put me on a 50GB package, NOT WHAT I SIGNED UP FOR!! few weeks later I receive my bill, for R1300!! When i initailly signed up for R499, this needs to be resolved ASAP!!!! I've called the CC, I have 2 dispute numbers, after being unsuccessful on the phone I went back to the Century City, only to receive attitude and no help whatsoever in resolving this mess up you people made! As a fist time customer, I am extremely unhappy, I will never recommend Telkom Internet to anyone, and I do plan on cancelling should this not be resolved!!!!