I have not been able to reproduce this issue. You should have approximately 45 seconds to hand the gold to the NPC before the NPC's offer ends. Is it possible that you handed the money to the wrong NPC? I know that I have done that in the past when there were a few NPCs bunched up together.Twice now I have been ripped off by an NPC over training.
Once last year by a ninja in new haven Atlantic. Now by Erito the mage on LA.
I click train in mage. He say's 272. I drop 272 gold on him, he say's thank you for the gift and I get a big fat Zero.
I started a new character with the normal 1000 gold. Now i'm down to 728 gold. Don't feel like wasting anymore gold on this Idea.