It sounds like a tricky job. I don't know exactly what your situation looks like but you should be heating the area that the bolt is threaded into. If it is aluminum it will take a while with the right flame and touch. Al really conducts heat. You will end up heating a large area because of that. Keep moving the torch slowly around the bolt hole for a while. have a long wrench on the head and apply force while still heating. It should eventually budge. Work it slowly back and forth if you can without going crazy on it. You will probably have to keep the heat on. Once you take it away the heat bleeds off. Be patient and careful. Good luck. Get some help.
