Cancellation department is a joke

I have been back and forth between the cancellation and accounts department several times now and no one knows what they are doing. I did a premature cancellation on the 30th of September. I went into Cresta branch and paid the cancellation amount in full. I called the cancellation department after that and they confirmed receipt of payment and advised that I would not be charged again. Now I get the bill for October and you are really charging me for my cancelled line again!!!! Why? This is theft. I already paid the settlement amount and now you are going to try and take EVEN more money from me? Why????