paying for insurance rapair instead of claiming on insurance

[nick9one1]

Last week I unfortunately stopped too late and bumped the car in front. There was very little damage but you would see some slight cracks in the paint where the bumper had flexed. The owner kindly gave me the option to pay for a repair instead of going through insurance - which I accepted.

I'm wondering what I should do to protect myself incase the owner tries to pull a fast one - takes the money but claims on insurance anyway.
I'm thinking I should probably pay the body shop directly, and maybe get something in writing from the owner to say the matter is closed?

How do others handle this situation?

[nick9one1]

thanks for the suggestions.

Bit of an update - I asked the other party to sign something to say the matter is closed once the bumper has been repaired. they are happy to do so.
I also suggested I could pay the garage directly - which they are happy for me to do. £500 + vat.