I had the same problem on wifey's passenger rear C30 Volvo, that uses same platform and parts like brakes when Volvo was under Ford ownership. Just rusted and seized solid. I also broke my Power-fist tool.
Just take it off and hit Napa store for replacement, was about $ 60 about 3 years ago. Don't waste time trying to repair.
Bleed the brakes, but make the wife help pump brakes. She will squeal while helping you, but your brakes will be golden.