Mtn Bad Customer Service ever

As an MTN contract user they called me December last year for the upgrade, with the terms that i will receive the same benefits as my previous contract before the upgrade. All that was a lie as i received new benefits which i did not agree upon. I then called for the phone to be returned to MTN and cancel the upgrade. since the 12 December last year these matter is still not resolved and they have their phone back. when i call they tell me they have escalated the matter to the cancellation department but still today to response.