Cancelled the account but still getting a bill from Jet

can i please get assistance here,we close the jet account but still getting sms that we ow you money. we have been to the store in Keywest twice now and no one can assist us. i am not going to pay what we ow cause we cancelled this account and they have the no service rendered to us. what should we pay you for? i dont want to walk into this store cause it irritate me how they treat old people. **** for pensioners and they move from Edgards without notifying the clients