MWEB Billing incorrect all the time!

MWEB billing is constantly billing my account in error with incorrect amounts, last month i wrote to them after account was paid and they billed me incorrectly, which they rectified. This month same story.... last checked my balance was R665 normal subscription, today its over R2200 in arrears. I tried calling and the airtime keeps running out, the calls are on hold for ages. I am tired of this pathetic service! MWEB call me back