Xpress will take more than they should

My wife and I had an uncapped internet setup installed a couple months back at our place in Ledibeng Eco Estate, and we have had nothing but trouble ever since. Besides the fact that its probably the most unstable internet connection, they take off more than they should. We have paid every month thus far and last month they debited my wife's account after my wife paid them as well, so they got double payment last month and we left it for this month as they are sitting with an extra payment, but they went and debited her account yesterday again. If Xpress don't reverse that installment or reimburse us then we will cancel our internet and bad month them on all social networks