disappointed and angry at MTN

I had contract with MTN and ended last year august ,I tried so many times to call them to cancel it without any luck now they tell me I owe them about R2000 ,and been handed me over to lawyer, how do u hand a person over without even telling them because I believe MTN have collections dep where they supposed notify or advised client about their account in errors of which mine was not was paid up but now I’m been crucified for not cancelling it of which I did try to call so many times to call then will be on hold for long and i have work to do instead of sitting on hold the whole day