@ my wits end

[SJ13]

I have encountered an inset screw{allen head} that I can't seem to conquer it is rounded and the said wrench won't budge it I've tried filing down the corners a bit to try and get it to fit further down inside I also filed down a flat screwdriver to fit down inside also but had no luck with either, since this is an inset screw on the chromed mirror I am hesitant of drilling it, any suggestions from you Guru's out there would be greatly appreciated