Bad service MTN

I am so fedup with MTN. I was phoned by Mtn, Larocha on 5 Oct 2018 offering me a data package on my current number because i am using so much data. It was called a migration. 20G anytime and 20G night time for R499 for the remaining of my contract period. I even confirmed with her supervisor as it is less than im paying currently. On 12 Oct 2018 i phoned mtn asking what happened as i did not receive anything. I spoke to Portia. She didnt know of anything. I requested that the audio should be drawn. I am still waiting. I phoned again today... Spoke to 4 people which dont know anything. I've had it. Cannot wait to change to another mobile company. This is not the fist time i experiene problems with MTN.