How long ago did you email them? I've never tried contacting them myself but other places have varying times for replies, more due to lack of staff than an unwillingness to reply.
Last year I emailed the Aberdeen Ordnance Museum, and reasonably quickly got a reply along the lines of 'Sorry, can't help, don't have any information on that'. Then several months later I got another reply off someone totally different there saying 'Here's a scan of a photo we have' (it was a superb scan, by the way).