Impossible upgrade

I was due for an upgrade 1st September went to an Mtn store wanted a laptop but was told about my credit limit so i cant get the laptop which costs less than what am paying at the moment but i dont qualify. I asked the supervisor at the store( O.R Tambo airport) who can i call to increase my limit or something his response was that he doesnt know, then if he as a supervisor doesnt know who is supposed to know? I called customer care 808 they dont seem to know what they are doing and they tell me to call *** which i did and they say i must call 808 so now m being sent back and forth, then some lady at customer care gives me an email address [Email Removed] i send the email and it comes back coz the server doesnt exist so please tell me what am i supposed to do now coz honestly this is fruastrating and am a loyal customer to MTN but i think il change my service provider!