Welcome to BCF. What car (model, year) do you have?
If it's just a stuck bolt, I've used a 50/50 mixture of ATF and acetone, dripped down around the hole. Let it sit overnight, then next day actually try to "tighten" it just a bit. That can loosen it up enough for the ATF/acetone mixture to seep down inside more. Tighten a bit, then loosen; tighten a bit, then loosen. Drip the ATF/acetone around the hole after every tighten/loosen round.
You usually find that after the first cycle, it will begin to loosen.
Let us know how it goes.
Tom