Overcharge with a zero balance useage

<p>I have taken out a smart internet bundle for R99 a month. Ihave phone in to put a limit of R0 when the data is finished. This has worked for the past months. All of a sudden I get billed an additional cost of R500 for data which we did not use. As when the data is delepted it stated no data and we did not get additional data to use. Please reverse this cost as this has happened on my other accounts also and it took months before I was reimburse fot the debit order that was incorrectly taken from my account. ********** 75</p>