How many times must one give notice to cancel?

July 2015 I gave notice of cancellation and to date the contract is running month to month when I make them aware I receive email that it has been actioned only to be bel**** again and again. Certain call centre agent by the name of Joel tells me that yes it shows on the system notice was received but somebody else removed it. must I now suffer for the incompetence of autopage's employees? I gave them another notice and ref no. A*** was provided. I wonder if this time this damn cancellation is genuine, after this I m gonna take my future business elsewhere.