Web and contract mobile purchase

Hi, I made a web purchase with contract, the day of shipment was not at home and the mobile was returned to o2 and I got my money back, the issue is the following, the contract is still in force? Or is it cancelled on its own? I read on the page that it is canceled alone, but I received a notification from the bank that in a week I will be charged a Silver that is referred to that contract, where would I have to communicate? Thank you