Contract Cancellation issues

Initially called to cancel my contract before it expired so it doesn't renew. Called again after expiration because I was billed again. Finally got it cancelled then I got billed only for insurance in August. I contacted them and they're telling me I need to contact the insurer who I had no contact with at any point before to cancel the insurance! I'm really disappointed because not only did I have to pay an extra month once, but I still had to pay another fee a month later after that and now I'm having to do all this effort to cancel the insurance as well