Bad sefvuce and *********** clients

My mobile contract ended in January and had called to cancel in February whereby I sent an email to make query on the contract instead I was told I am in arears and until the contract is canceled I am still obligated to pay. Also my query was that I gave not been using their services so how is it possible to be charged for service not rendered if I remember well when I took that contract it was for 24 months and was never told after that I will need to give notice. Notice for what ad I have obliged to the contrac. I think this is a way of ripping us off.