Bad Service

I am not happy with the service provider company, my wi-fi is disconnected due to insufficient funds today 29 September, my agreement with vuma is to debit on the 1st of every month. On the month of August the same happened and i made another arrangement whereby they have made a agreement, on the 3rd of September debit order payment was made. Today is the 29th September the 30 days period have not lapse but the service provider wanted to debit, in which my account didn't have enough funds. Despite our agreement to debit on the 1st of every month, the service provider continue to act outside the initial agreement and disconnect me. The matter is urgent since I use internet for my work.