MTN cancelled contract and now wants the client to pay cancellation fee

I cannot start to explain the incompetence of such a high profile company. I upgraded my contract and 7 days later MTN cancelled it and now wants to bill me for the cancellation of the contract.

I DID NOT CANCEL THE CONTRACT MTN - YOU DID!!

MTN now wants me to pay the full cancellation fee before it gets sorted out. WHY? MTN THIS IS YOUR MISTAKE and yet you cannot fix it. I have had my mtn contract for 24 years - time to change if you cannot sort out your mistake