Have you tried the HAMP escalation line? call 8889954673 and ask for the escalation team, which turns out to be a group of HUD counselors in Penn under contract with Fannie to serve as an interface to
"encourage" the servicers to do what they agreed to do. They will want your client with you, at least in the beginning, to approve you talking to them. Then they have phone numbers for better contacts at
the servicer. I tried it last week for a BOA account. Not a miracle yet, but some progress was made and they were at least in the US and were willing to give me their name and agree to regular phone calls to
resolve. It was a mod request, not a short sale, but the basic procedure should still work.