MTN SERVICE

I signed a sim only contract with MTN. We recently moved towns and there is limited service in the new town due to power outages and a tower with no back up battery. Their service department acknowledge the problem and admit they have no solution pending. Despite numerous phone calls (they block your no. once they know you want to cancel) emails to Customercare (unanswered) and retentions, plus visits to their store for over 3 months I am getting nowhere. MTN are not honouring their contract and it seems I have nowhere to go. Last visit to the store +- 2 weeks ago - I was promised a consultant would call. I have not heard a word?