Suspend line on credit??

MTN have now blocked my line a second time in four months. It seems that they do not know how to use a billing system that works. They implement a credit limit of R816. My monthly bill has not exceeded R677 since I have been with them, yet my line is suspended? Seems they bill everything, then apply free minutes/sms at the end of the month, making my account seem large to them, but I have no visibility.<br> And then the staff in the branch are not able to assist, as they don't have access.<br> Call centre is not working either. So a continuation of \Excellent Service"in RSA!!"""