Rear deck spoiler leaking

does anyone know how I can fix my rear deck spoiler? Last year I took it to the Toyota dealership to be washed and one of the brushes got stuck beating the rear deck spoiler which broke one of the bolts that is molded into the actual spoiler. Now whenever it rains I get water inside my trunk. The bolts themselves are molded into the plastic and cannot be replaced that I can see. There are also some plastic snaps, but the one bolt on the driver side sheared off. I just want water to stop coming in my trunk

 

I know how to get the spoiler off and such. The bolt on the left is broken and is molded into the plastic. I just got some silicone and put around all the holes and snapped and bolted it back down. Hopefully that keeps the water out. The dealer said they are not liable for damages from their car wash.