MTN doesn't want to fairly terminate a contract

Now that I want to terminate my contract (which ended in October), mtn wants me to stay with them for another 30 days which is not stipulated in my contract.

When I wanted to cancel it last month, I was told I would have to wait till the contract ended. Now that I call them, I'm being told something else.

They are also charging me termination fees, and I will only officially be out of their contract in January.

Last month I canceled a contract with no termination fees, no 30 day waiting period, no issues. So why are they coming up with new rules now. I have read my contract, and this is not what I signed up for