Reustrated client

I've been paying my with MTN since dawn of our contract but as I am writing this review, my lines are suspended MTN claiming that M owing them money. I've been calling countless times to the Call center and sending my proof of payments to all agents I've spoken to, even went as far going to their store 14th Avenue but my problem was only solved for a month and everything went back... Why can't someone just allocate the money I'm paying... One of my lines is due for cancelation I can't cancel it because of the debt...