Worst company to deal with for after sales issues!

I have signed up with Mobile Talk during the end of 2015 for a 20Gb per month data package. Since the start of my contract they have debited R150.00 per month extra on my account and is still doing so. I have made several calls and e-mails to the call centre asking for an explanation and or refund but no luck. Everyone I speak to says that they will escalate the issue and come back to me but nothing gets done and I am still paying extra. <br> <br> Unfortunately I have agreed to a 24 month contract and cannot cancel without penalties otherwise I would cut myself off from this supplier long time ago!