Unfair cancelation of my MTN contract

I had cellphone contract with MTN, one for myself and other for my sister and all in my name. This year my sister phone was ****** and on that same weekend I also damaged my sim card, talk about bad week. Then I called the mtn customer care to deactivate the phone, and asked what is the total value of the contract should I wish to cancel and take a new contract. When I went to mtn shop to do a swim swap I was told my contract was on pre-termination stage and I needed to call their legal and retainment department. I did all these and took me close to three weeks back and forth using my own airtime. Then afterward for them to tell me I had to settle the account in full and the number will be turned to prepaid afterwards. I never asked to cancel my contract. Mtn will call u millions of times and send u millions sms if they want u to get a contract and renew it. Why they never used that same energy for canceling of the contract which I never asked for. Mtn want you to pay those unreasonable penalties and charges they now will charge you when the contract get canceled, totally unacceptable.