Need advice and also a warning.

Didn't see it mentioned, but I hope you have all the receipts from the parts you bought and turned over to the shop.

If so, that should be a no-brainer to get back unless they have used them on other cars (it happens). At least there's a defined value. Take those and the BOS with you when you talk to the cops.

Also hopefully, the shop can produce a title that matches the VIN on the bill of sale, otherwise the price on the BOS should be refunded.