Cancel this contract

I took contract in June 2016 for 24 months, this early around March i started sending cancellation for the service and no respond from service provider, i went to their several store with no help and i called the call center they send from pillar to post. even now i am still getting threatening message every time i reversed debit they made in my account cause our contract end in June 2018, so i am longer they are client. i reported the matter at ombudsman still no help.