Still paying after I cancel my contract

At November 2014 I port my cell phone number to another provider. My contract expire on the 8th of November 2014. I called into the cancellation department at the end of November to confirm cancellation and I was to I will receive my last bill at the end of December. Not a surprise I received a bill for January 2015. When I spoke to Max the supervisor he said that he saw their mistake and he will personally cancelled everything and instruct the accounts department to refund me. He even gave me a reference ***.<br> <br> I'm still getting invoices and the debit order still goes of at the end of the month.....