What should I do?

I told my work about three months ago that this Monday I need to be on dayshift due to my girlfriend having to go to college, I talked to the HR guy today and he says he still has to talk to the owner, that’s in another country right now, taking a trip, so I won’t be able to get on dayshift by Monday. They knew for three months and didn’t talk to the owner during that time at all is there any advice anyone can give me on what to do?