Loan At 17?

In October 2020, I insured my first car. Going through all of the details, I was made aware that I would be paying back a different company, who are a well known finance company. I was 17 at the time.

Around 4-5 months into my insurance policy, I decided that I wanted to cancel the policy and started using my grandads car instead, as he barely drove his at the time. When I called the insurance provider to cancel the policy, they told me that I could cancel but I’d have to pay the remaining balance to the finance company as it was a loan. I asked them how that was possible as I was only 17 when I started the policy. They said that I would’ve gotten a parent to sign it, which I certainly did not. They then said that it was legal but they wouldn’t be able to do anything if I didn’t pay anything until I was 18. Then they’d be able to get debt collectors involved etc.

Though it is years later, it has recently been something I’ve been thinking about a lot. Surely this couldn’t have been legal? Any advice would be much appreciated!