Do they still have a working telephone line? How long has it been since you heard from them?
Under some circumstances I'd consider contacting the police. A very large gunshop near me went nutz and closed the doors with many firearms that were in for work, or whatever, locked inside. The State Police had to find the owner and tell him to contact everyone with info that they could pick up the gun on the next two weekend because he would be there (or else).