Medication can be helpful, but it appears it hasn't worked. CBT is a form of therapy that is supposed to be the best for treatment of agoraphobia, but he has to be willing to go and to do the things he's afraid of eventually. The longer he avoids, the worse it gets. The fact is, some people get better, some don't, but in order to get better you have to be very motivated and willing to work hard at being very uncomfortable for awhile, and that's just what the disease makes you not want to do. For a case as bad as his, usually medication is used to ease the anxiety and then therapy is used to help solve the type of thinking that caused it, but there's never a guarantee anything will work and medication can be problematic as well. The only thing anyone can offer you is to get him to keep trying knowing it may lead to a lot of failure but is also the only way to success.
When my anxiety first appeared it was going through a line at the grocery store. I remember thinking how am I ever going to sign my name? Well I chickened out and fleed the store instead with all my groceries behind me.It scared me to death!! . My son was a little boy back then and said "Mommy, why are you leaving the groceries behind? I couldn't explain why.That's when I went to the doc and he prescribed Xanax for me and it worked. You say Xanax doesn't work for you? You can get higher doses of Xanax but if they don't work either than getting well educated on the subject helps tremendously. I found out that there are different types of anxiety. Like I have "free-floating" anxiety which means there is no real reason for my anxiety. Sometimes we can be "hard wired" for it, or some event in our childhood that tramatized us. I had plenty of that. When I saw a psychologist she said that I would need "Psycho-analizgy (misspelled) to get to the bottom of it and I said no thanks at the time. Perhaps you might get rid of yours like this. Whatever you do my heart goes out to you because I am a fellow sufferer. One huge suggestion though, do not let it make you a prisoner of your own life. Life's much too important for that. Also large bone exercise helps and a good diet does too.