MTN /Rewards contract I am not aware of

A year ago, I downgraded 2 contracts to month - to - month contracts. Last Wednesday, 9th of January, I went to MTN Cavendish Square to upgrade my son’s contract to a 24 month one, so he could obtain a new phone. Upon doing so, I was informed that this could not be done, as I have ‘signed’ a 24 month contract with MTN. Why would I sign a contract with MTN without obtaining a new phone as part of the deal? After much conversation, the assistant at MTN contacted Rewards. This is the company that saddled me with this ‘24 month contract. ‘They operated from a call centre. I asked them for proof of the contract. It is not forthcoming. I then spoke to Tyrone at Rewards who told me on 3 separate occasions that this ‘contract’ had been cancelled on their side and that I am free to take out a new contract for my son. It is now Monday, the 14th of January. I asked the assistant at MTN Cavendish to check the status of the ‘contract’ only to be told that it has still not been cancelled. Could this Rewards company be investigated? How can I be party to a contract I don’t have a copy of? MTN at Cavendish have told me that this happens all the time with their customers. I am now sitting at MTN Cavendish yet again waiting........