Impossible to cancel contract, evan after contract period has finsihed

I have never once gotten any comunication about my Fixed LTE contract, no invoices etc, now my contract has expired and gone month to month (at a higher rate) I have tried multiple times to cancle it, yet all they call center people do is pass my call around to multiple different departments, I don't have the time or money to waste holding on the phone for someone to decide when or if they can help me.... MTN why do you make things so difficult?!?!?