I would send a snail mail letter. Also explain that you would like to be a customer of theirs, but their obvious lack of knowledge ushers you away (might want to word that a bit better!). You could even offer to help them out. Snail mail letter would be best I think because it would make them feel a LOT less defensive. An email would likely just get a nasty response. With snail mail they'd have to take effort to respond, and would likely only do so if they cared.
