MTN Extremely poor customer service

I have been trying for some time to contact Mtn via the app or 135 to get assistance regarding an incorrect debt amount. The app tells you due to an upgrade you cant do it on the app and please phone 135. On average it takes about 7 min to get a person on the line,one just cut me off the second person wasnt even able to understand my problem let alone assist and just dissappeared of the line