Cancealtion chaos

I tried to cancel a contract, recently and was told everything was fine and I won't be billed again yet last month was charged, and now again only this time it's a little bit more, when a client says cancel they must cancel and not forget about it ,seriously, and will not be paying the bill as it was supposed to be canceled I followed what needed to be done, this is no fault on the consumer, it needs to be sorted.