wow what did you use, elmers glue? I've never seen bondo or any product suitable for making a bezel melt before.
Anyway...just redo it with a filler that won't melt, shape it up, prime it, and paint it. I'm not quite sure I understand your question...are you asking which primer you should use to make the painted bondo match the existing plastic? I don't think it matters that much, unless you paint really lightly the primer won't show through at all, just pick a paint that matches the color of the plastic.