MTN keeping me hostage in contract.

MTN,much like Telkom is keeping me hostage in a contract that was supposed to be canceled in March of this year following its 24month duration. I got the contract in Nicolway as that’s where I worked,but I soon left and they did not tell me that when it had reached its “expiration date” I was supposed to go to the store/call the retention to cancel it. I find that quiet odd because said Info is never shared with customers. The problem is that my cellphone number is and umbrella to two contracts for an upgrade and one for my router. So now they disconnected the main number. I no longer know what to do because their supposed lawyer served me with a 72hr notice but they are won’t making it easy for me to pay for the two existing contracts as I did say I was keen. And they spiked the amount I was supposed to pay from 299 to 1180 and I fail to understand how they got to that. I’ve called the service champions and they all tell me that can’t transfer me to the cancellation department then I DM’d MTN on Twitter and they said I can only do it in 30 days,so I feel like they won’t let me out? Won’t let me pay? I don’t know what they want me to do. Can they please cancel this contract as it’s affecting my credit and I think this is a small misunderstanding.