Cancellation of contract and incorrect billing

I have a very bad experience with this company, every time i think of it i get even more angry. I took a contract with them in April 2017 which expired in April 2019. Went to their different branches to cancel after the contract expired no help im referred to the website. Registered on the website and no accounts are linked on my name. They still have a nerve of debiting my account after the contract, for a data that i am not even receiving, after i blocked these payments they decide to black list me. I seriously need this sorted out as i do not owe them anything, ive tried by best to cancel the contract but they make it impossible to do. I still have the copy of the contract and screen shots of the website not allowing m cancel. Can some body do something!