Billed when Contract/account closed

It is always difficult to get hold of an agent at the Autopage call centre as they always redirect to a self-service menu and there is no input key to get direct contact of an agent. 2 months I sent an email to autopage given them the notice period to cancel my contract with them, I did get confirmation that the contract/account will be closed on the 20th June 2015, but on the 1st July 2015 autopage debited the contact amount from my bank account. I have since tried to get hold of the accounts department but am unsuccessful, I do not want to be billed again the following month and demand a full refund of the amount debited.