Wrong debating amount & poor service

I’m so fed up with wrong billing and poor service I’ve got 2 contacts with MTN & both are top-ups If I used all my data n minutes I recharge them by myself last month mtn decided to deduct R1000 instead of R700 I went to Prominade Mtn branch to find out what why a very rude and unprofessional consultant Channel told me that I have suddenly changed my data usage to 310 I told her I didn’t & asked for proof she couldn’t provide it I then asked for her manager she told me that his on holiday . Bcs there must be something showing that on this particular date and time I made certain changes on my contacts.This Month mtn decided to deduct R1700.23 & this annoys the hell out of me bcz I have to reverse every single time they make this nonsense it costs me bank charges.