USELESS !!! BAD SERVICE

I am a client for more than 11 years with MTN, i would suppose that i will be a good client that pays everymonth my bill ontime. I have upgrade online since 10 years ago for the reason not to stand in a que in the MTN shop for hours to be helped. I wanted to get an extra contract an Iphone 7, i am struggling since the 8th of August online no replies emails to me "someone will phone you" ? really no one phones me after numourisly emails and calls no help!!! Today the 20th of August i was in luck to speak to someone, everything went well and then she says I must go into a shop to help me because if she add the amount then my Credit dont allows this!! No one at the Call centre can override this I must go into the shop! This was the thing i wanted to avoid doing... why are there a Management or Supervisors that can not override this and give SOME SERVICE??? THIS IS BAD BAD SERVICE!! I know they dont care about their loyal customers so why must i keep my contract with MTN? THEY ARE USELESS