Exhorbitant, unfair ******* charges from MTN

I contacted MTN over a week ago. I was offered a contract upgrade with an upgrade charge of R350 - stated and confirmed on a recorded call. I also reconfirmed a monthly charge via the call center and at no point was I presented with any extra fees. MTN then give me a run around, and after many painful days, I eventually get a device from the branch. I got no contract to sign, no presentation of or copy of documentation to explain the so called increased fee, no signed documentation sent to me - nothing!!! But MTN charged me nonetheless! Soon after, I get an invoice with a fee that is 200% more than what was promised on the call to MTN Retention’s. After waiting more than a week for MTN to get back to me, I am still waiting for a response!! This is treating customers unfairly and potentially *******. MTN’s service and customer orientation is absolutely disappointing and they seem to adhere to very shady business practice!