Stuck caliper bolts

[hfrancis]

I am having issues getting the top bolts on my 1998 boxster. attempting brake pads and rotor change. the lower bolts come all the way out no problem, but the tops loosen up the gets lock tight as they come out. it is the craziest thing i have ever seen. this is an easy job that has turned into a nightmare. i have tried heating with an Acetylene torch. I am a little nervous about letting it get too hot, but i have heated it enough but the bolt will not turn. any suggestions would be welcome thanks.