I hate the be the bearer of bad news, but it's not going to be likely/easy. The only thing you can really do is ask them for a call to explain your situation.
Ultimately, it's very hard to transfer before starting, and especially moving across countries.
Your better bet is transferring AFTER 1-2 years at the firm
I've transferred a few times within companies and have the following advice:
1) Build a stellar reputation - do good work, work hard, and be known as "the guy/gal" for xx
2) Build your network - network agressively (yes, networking doesn't end once you've gotten the job offer). Make sure you're known by and have allies in people who make decisions such as staffing managers, Partners (specifically those responsible for recruiting/resources and who are heads of industry/function verticals), etc.
2) b). When I say network "aggressively" please don't be needy/annoying :) There's nothing worse than someone who is obviously working the room or trying to please!
3) Look out for opportunities - as mentioned in this Q&A already, look for office transfers, short-term projects, ambassadorships, etc.)
4) Practice patience and be flexible - how long have you tried for? This might take a year. And you need to be ready to go at the flip of a coin.
Bide your time, keep pushing, be smart, and you'll get there!