Horrible service from Mtn

I did an upgrade in the Rustenburg store, they first got my debit orders amount wrong and charged me a different value than I signed for... I then spent 2 hours on the phoen with their call center to correct I was also promised a 20gig promotional data when I upgrade which I did not receive now the store can't assist me over the phone and the call centre is referring me back to the store This is just horrible service from Mtn