I'm not sure what PDB is, but in F they bring you whatever you ask for if they have it on board. They may not have had OJ (although, that would kind of surprise me)

As for change fees, I'm not sure if that counts as a change or not. You could just call and ask them. Even if there is supposed to be a fee, they may waive it and just charge you the fare difference if you ask nicely. (and, of course, if you used the VX CC, the change fee is waived)