MX5 with Engine problems :-(

[Summertimeishere]

Hello All

I'm new to the forum and looking for advice on my 2006 MX5.

I absolutely love my car but made the cardinal and fatal error of running it on low oil. I heard the dreaded knocking noise and took it in to the garage who said it sounded like the piston head. The garage thought it wouldn't be worth fixing, but suggested adding an additive to the oil to help the engine and reduce the noise.

Has anyone had experience with any additives that might help? Or is the car a total gonner?

Any advice is gratefully received!