It's good to see they have a rep here on the forums. At least we might get some sort of explanation. I can't even imagine what it would be though.
I can totally understand if they were out of stock, or a delayed shipment, or just flat out offered a refund (which they did offer)...but to ask for an extra $10? I've never even heard of a reputable company doing that. They can't possibly think that would go over well.