Well, i had some email exchange with them, and they usually reply in one or two days, the only one that i received in late was 3 days, and i think that this is due only to some festive days and different timezones, so i think is not their guilty for sure.
Other than this, the person that replied, Susie, was always gentle and, also with my bad english, we had no problems arranging the order i made.
Then, you probably just need to wait a bit and left them the time to read all the emails and to reply to all the peoples that write them for informations ..... remember that it's not a private, that can receive few mails and have all the time to reply, maybe also sunday ..... they're a company, and all their times are based on work time, and also with the different timezones, maybe when you write them, it's night there, so need another day for read and reply, maybe more if the emails that they receive daily are a big quantity, and so on.
Indicatively, as personal experience, when you write to someone on the other part of the world (not just o-like, i'm speaking about anyone, here), allow also 2 days for the reply, if is a private, also more if is a company, or if there's sat / sun in the middle
