I've never heard of the diamond desk transferring someone over.
If the points don't post just call the diamond desk and complain and I'm sure they'll do a manual post to your account since it's only 500 points.
I've had a couple friends that have been called by them and there are a few threads on here about it (not sure if they have ever called me since I only take calls from numbers I know and if they have they haven't left voicemails) and a couple times I've stayed at properties where they have offered me points or a gift to go to a HGVC or Hilton Club desk at the hotel and I don't bother.
I'm surprised Hilton would get involved with a scam like this