I'm sitting here with my jaw nearly on the floor.
One year ago, the same thing happened to me! I called a number and thought it was Admiral. It wasn't, it turned out (down the line) it was a company I'll refer to as ALS. I had no idea I wasn't talking to my real insurance company. Not a clue.
Luckily, I was sent a letter from Admiral saying they had been notified your car was in an accident (due one of the two other third parities providing my car reg in their claim). When I called the number on the letter it soon became apparent what had happened. I remember screaming in shock when the call handler told me I had been scammed.
I only had the hire car for two weeks in the end, but what happened over the next week was hell. ALS were absolutely horrific to deal with and kept my car basically 'hostage' until I paid their car hire bill, which I duly did to get my car back. They were threatening and abusive.
I called the police, the financial services ombudsman (marginally helpful) and scams helpline. I even tried the press. Literally no one helped me.
I actually had a sort of breakdown over it and have been on anti depressants ever since.
I just thought it was me. I never knew I wasn't the only one. It's been hell, absolutely a nightmare.
I finally have been reimbursed the money this week, from the third party at fault insurance company. I never thought that would happen and it's been so triggering even though I got the money back it upset me all over again.