the same thing has just happened to me. msc research (done at uni 2) accepted at lovely international conference, phd (at uni 3) has very little to do with msc therefore uni 3 would only offer about a third of what i needed. really couldn't afford to self fund!
the second author is presenting for me which means it'll still be in the proceedings. do you have a second author? if not, perhaps your supervisor is attending and may be willing to present? you could add them as second author...