Ex using my address for new auto policy

Hello,

As the title says, my ex has started a car insurance policy at my and my partner's address. He is very high conflict and has always been quite shady, so while this isn't super surprising – I'm not really confident with how the insurance company is handling it, so I'm looking for ways to escalate/report it so the policy is cancelled immediately.

I have called the insurance company twice and they said their underwriter would "look into it" but we just received more mail with "important insurance documents".

Any help is much appreciated.

*ETA – He never lived at this address. I have moved twice since we broke up years ago and he has followed me both times into new neighborhoods. Our zip codes at this point are only one number off, so I am just confused as to his reasoning doing this.