Hi,
We're a tiny company, and don't have a phone number for the public at present. Where did it say you need to call? Was this with the BMT Micro order page? I'm the head of Arcen, and I don't know anything about that, unfortunately -- I'd imagine you'd have to call BMT if anyone, but then again I have no idea why it would want you to be calling somebody in the first place. Sorry for your trouble here, but if you have extra information, that would be great.
I have bought the game myself through BMT with a debit/credit card, to make sure that everything was working fine, and it went right through. If you're looking for the base game and for some reason BMT just won't accept your card for some reason, you could always try Impulse, Steam, or one of our other partners, which use a different kind of online store. Or Paypal works at any of the above, though I suspect you do not want to use that if you are not already doing so.
If you're looking for the expansion preorder, our site is currently the only one that has it, though Impulse will have it soon (and our other partners will have it in a month or so, closer to full release in January).
Again, sorry for the trouble here, but there's definitely no need to call as there's not anything I could do to help with payment processing -- that's entirely handled by our e-commerce partners, and it's a mystery to me why they would ever ask someone to call us... :/