Try this

Urethane Supply Company ( USC ) - Plastic Repair and Plastic Welders

http://www.urethanesupply.com/

They have lots of great info on how to ID and repair plastics. Most modern plastic parts are marked with the type so take it off and have a look.

I repaired the front bumper cover and plastic support on my SL with their airless welder ( soldering iron type ) , it works great. Read the instructions and ID the plastic first as some repairs require melting the part you are fixing and others not. You also might be able to use their epoxy to make the repair.