Alas, there is a thing out here called "the Hollywood no." Because so many people are scared of pissong somebody off who might later end up in a position of power--or who might totally overreact--the two responses are an enthusiastic "yes" and dead silence. They won't answer emails, won't be in the office to take calls, and so on.
It sounds like you're getting the Hollywood no. Sorry.
I will say this, though. Try every angle. Don't just go for the publicist, try his agents, his managers, everyone. If there's a number or an email address, use it. Don't carpet-bomb them, but if you get a no from one politely move on to the next. A lot of these folks are following their own agendas, too, so they all have a slightly different view of their client. One might say no, but the next might be all for it.
I interviewed one of the creators of Eli Stone
a few years back, and he told me that when they originally wrote the pilot they put feelers out to George Michael's people and got back a very harsh "absolutely not--we won't even show this to him." They were heartbroken and tried to figure out who they could replace him with. Then a month or so later they happened to run into one of George's other agents and were talking about it. The guy said "Really? I think George would love
that. Let me talk to him about it..."
I think George Micheal ended up appearing in at least four episodes
of Eli Stone
, and they used his music in another three or four past that.