CGB is on of the places I always hoist the dinghy. I suspect that 25hp engine was the target. West End is the other place I always hoist the dinghy.
Sadly if they took it off your boat I doubt you will see it again. The engine has probably already been pulled and resold. If it was taken off the dock there it’s often kids joy riding and those usually turn up.
I don’t know what type of insurance policy you have but if under the charter company group policy they might be reluctant to file a claim. They don’t want to drive up the premium. If that is the case you might have to enter a negotiation with them on a replacement.