They still visit the forums. They were last online here about 16 hours ago.
I'd try the contact information form on Mr Bitcoin or contacting them by PM - they do seem to be on here quite often even if they don't post.
https://www.mrbitcoins.com/contactusOne thing I did notice when I looked up the registration information for Mr Bitcoin is that the principal place of business address and the address for the service of documents is different from that listed for CryptoXchange. It's possible that they've relocated the business to a new address and been unable to keep the same phone number.
They do seem to be a lot less accessible than in the past, and that's a pity.