Creative Ideas Sought: Coach ticket purchased @ a Bus. Class rate

[pilot]

I was invited to fly to Moscow and the ticket was purchased by my host. When I received the e-ticket I noticed that the rate that my host paid was roughly the price of a business class ticket (~7800 Sing$). Yet the e-ticket clearly says Y class and SQ rep confirmed that.

I have already tried calling the (apparently large) Russian travel agency where this ticket was purchased. After spending over an hour tossed around between a dozen or so different agents that spoke very poor English and seemed to have zero interest in helping me out (I heard giggling in the background), I gave up on trying to work through them. I suppose that I could point out to my host that they overpaid but my guess is that they will ask the agency to refund the difference rather than get me the business class ticket.

My question is do you have any suggestions on whether and how I can try to get the ticket converted?

Ideas will be appreciated.