Bad, poor and pathetic treatment

I had a contract with netstar for 3 years, the contract expired in november 2018 and they never bothered to contact me and let me. Instead they continue to debit up until it came to my attention that it is expired. When i tell them i want to cancel they told me i had to make a 30 days notice for a contract that expired for more than 5 months. I wonder how they run their business. I also requested a document that state that the contract is cancelled, till today i haven't received it. Very bad service.