Crossthreaded window motor screw

Whilst deadening my doors I figured out I could easily take the window motor off. This was fine on the passenger side, but on the drivers side the top screw has been cross threaded and will not tighten or loosen. I think the dealer did this when they fixed my electric windows (had I known it was just the motor I would have done it myself!!).

Suggestions on how to sort this out? I'm guessing I am going to have to hack the head of the screw off? :-(

Can you buy the little black screw posts that the motor screws in to? Though I guess that means taking the inner panel off to put the new one behind it? Possibly just take the window out and see if I can manage to get a new one in from there?

B*stards!