Nothing but one big headache since going with MTN

It has been a constant struggle since day one when I got the contract in August! I am on the R399 per month MyChoice100 contract with Iphone 64Gb. First month they try to charge me R809.74! Eventually got that fixed. Then MTN claimed I made international calls that I never made & that later 'turned into sms' (?) & still waiting on that to be credited and basically been forced to opt for the Itemized billing. I've been getting out of data sms' even though when I check on *141# I have more than enough data & also keep track of my data usage (don't tell me about background apps) Now today I get another sms that my data that was loaded on the 14th has expired!? how? and get smart remarks of data expiring after 30 days when I contact the branch? Note it's not been 30 days. Also again they are now trying to deduct R514? what for? I use the MTN contract app and why is it then that that say R514 but branch says otherwise???? If the app is giving me wrong totals then fix the app. Struggled for over a month to get my address corrected. All I get is more problems and no solutions to them. I hardly ever get feedback unless I call back or threaten with posting on here so here we go then.