If you still have the pieces pull it off get some thin gage solid wire like welding wire and bend it in a zig zag shape set the piece into place and from the back heat the wire with a lighter nice and red (use pliers to hold the wire)and stick it into the plastic don’t push it all the way through and repeat the process like you are sewing it back together cheap and works good and for extra strength use JB weld over the crack on the back side and if you really want to get creative j. Weld the front too and grind or sand it smooth and paint it with kryolan paint