Clarity on my MTN contract

MTN suspended my services saying I must pay for cancelation of contract which I did not cancel, I have been calling them for 5 months to cancel the bill limits of R350. 00 that they giving, so I wanted to pay only the agreed contract amount, so every month I was calling them because it was never canceled, so the last time I called I was surprised to see November invoice of R10300 , 00 I called after November deduction of R3000. 00 they said they will investigate, until now I haven't received any feedback, I tried to call them even in December still they take me from pillar to post, cancelation departments said my contact is still active other department said they can see that the was no where it app that I canceled my contract, so I'm confused because they're saying they will investigate but they sent messages that I must pay that money.