No joy from MTN

I have already registered a complaint about the following:<br> I used data between 12am and 6am on 26 August 2015. this was supposed to be deducted from my night express bundle, but was taken from my regular bundle. it was more than was available in my regular bundle, so a charge of R285 was added to my invoice. MTN Data Validation responded with an email stating that according to them there was no problem and the charges were correct. I rep**** that it could not be possible. they rep**** once more, saying they have credited the account with R148,62. This has not been done however. The fact remains that their system made an error and I am not going to pay for that error. if they debit too much from my account, I will do a stop payment at my bank. I will then manually pay the account with the correct amount. I am sick and tired of indifferent attitudes and poor service from MTN.