Unfair treatment.

I have a contract with Vodacom and I have been paying on time without missing any payments until I was overcharged in June but I disputed the amount and they reversed it. Now my account is in arrears because they are refusing to reverse the penalty fee that is a result of the overbilled invoice which was an error from their side. I'm still paying my account on time but they have blocked my internet connection for the 2nd time now because my account is in "arrears". I have tried get help from customer care a countless times.