Sounds like your car has been written off as B.E.R (Beyond Economic Repair) by your insurance company, i.e it'd cost more to fix than its insured value, however since another party has decided that they'll spend the money to repair the vehicle then as the car is now the property of your insurance company, then they can do with it as they wish.
However, since the car had been written off by the insurer, why would you want to keep any keys relating to the car? Only a question, I'd have given the keys back to the insurers, as the car became their property as a result of the insurance write-off, therefore no-one could ask for any keys from you.