NETSTAR REFUSING TO CANCEL MY CONTRACT-pathetic service

I have been trying to cancel my NETSTAR contract since 17th August 2022, but NETSTAR keeps invoicing me. This is totally unacceptable. I was invoiced again for October, and I paid, yet they refuse to cancel my contract and still insist on billing me nonstop. Please cancel my contract, my car was sold in August 2022 already, yet I am still stuck with a contract that cannot be canceled. I keep being referred to my signed contract, yet they cannot produce a copy of it! This is the worst service I have ever encountered - paying for a product I am no longer using!