Have you tried dive shops? I've heard people go there to get re-fills if it can't be done at airsoft stores or game sites. Might need your own adapter..but i'm not sure, don't know much about HPA atm..
I think Escarmouche have their own refill gear, they double as a paintball site and from what I can tell the tanks refill the same way? Probnably best to give the owner Mark a message on Facebook.