Lack of Service - Shocking

How do.you rate lack of service. I've been to branches called them to speak to their 'Champions' and sent a number of emails. It's looking as though MTN do.not have an efficient accounting system. The agents agree with you, log your query and next thing you are billed for what you shouldn't have been. Told month to month contract is cancelled. Really - no you get another bill! The worst is if you only pay what the agent tells ypu as she's cancelled the contract, your phone is blocked by MTN (Not their phones either). We are pensioners and cannot keep paying money to MTN.who clearly do not have a sound accounting system. I did not take a new contract & made it clear to Telesales. Next I'm given a heavy bill and no longer after years via debit order. Obvious the agent knew I hadn't agreed so made it a cash deal so she could claim commission. Ive asked MTN to listen to the recorded call as this agent has committed ***** but all requests are ignored. Totally frustrated and very disappointed. Want to get as far away as possible from MTN.