poor service and rude stuff

MTN Carlton Center and Ghandi Square are nonsense , i have been going there from 5th November up to date ,to do sim swap because their self-service is no longer working, i couldn't get help and the stuff is rude on top of that , have gut to tell us customers where we can report them because no one will take action and pity because the sim card i have been using it since 2006 and i used it for my banking, applying jobs and now i am told my sim is blocked by mtn Please help me