MTN contract cancellation - impossible at this stage

Through my own negligence I ended up with a 2 year contract iso month-to-month as I requested almost 2 years ago. I now want to cancel that contract but after spending more than an hour on the phone over 2 calls with MTN (135) I'm still no closer to getting it terminated. I received 2 vastly different amounts to cancel the contract and neither consultant seem interested in helping me by giving me useful information. I've been with MTN for 28 years now, still with my original number, but can't seem to get them to cancel a contract with me.