Someone keeps using my phone number for personal reasons

For over a year now, some guy keeps using my phone number for account registration, flights, loans etc.

I’ve gotten his email from one of his flight reminders and sent him a message saying I’m canceling his flight if he uses my phone number again. He stopped using my number for flights but has now gone back to using it for other non-important site registrations. I would also get calls from these companies following up on whatever they are.

I …

account email etc flight flights loans message my number personal phone phone number privacy registration reminders