I have had to remove my spoiler from the boot and despite filling the spoiler hole with wd40 I have had to drill the heads of the fixings, I am now left with a small amount of thread showing, I have tried some molegrips on them but they are not budging even tried some heat on them without success, anynideasvhow to get them out without wrecking the boot?

 

Grind off what's left and drill out and tap.

 

grind flush and fit some new m6 rivnuts refit spoiler with stainless fixings and copper grease on threads. before fitting cap put a small amount of grease to stop water getting to fixing.