bad service

Being a client of Mtn for 15Years with failed i paid my bill every month for 15 years I feel disappointed with the service I received from Mtn. A month ago I upgrade my phone and was promised to get 20Gig free and still not receive. Besides not receiving My Gigs it took them 14days to activate my sim card im calling my consultant Brain at the Zevenwagcht branch and since the upgrade he giving me issues and promises he can't forfill i called him today again to enquir about my gigs he tells me I have to call the customer care nr cuz he can't help me or I need to come into the store. I feel that he did not do his job and why should I come into the store for airtime that I was supposed to receive already