Funny thing: I followed up this post with a reminder to Wizkids that I'd requested a package in September and that its status was unchanged. I had emailed them in early October and got no response. This time they said "don't sweat it, somebody will review your request". So hopefully I'll get a card in a few weeks.
You're missing only one card out of the entire deck? That's very strange.
And when you say you're getting no where with WizKids... they usually don't reply to a component request. You place your replacement component order and then wait. You won't hear a peep from them, and then a few weeks later your components are sitting in your mailbox. Or since you're in the UK, it may be 3 or 4 weeks?
That's been my experience with them, anyway.
If you don't have anything happening for you, I can perhaps help you out via geekmail, when I get back to my game collection in a few days.