dealer messed up keyless entry. what do i do?

i bought a 2007 prius not too long ago. the original keyless entry and start worked fine.

we bought a 2nd keyless entry as back up from a toyota dealer and took it to another toyota dealer to program for keyless start and entry on another day because we did not have time that same day.

the 2nd keyless works fine but now the old one would not. it doesn't work for keyless entry or start. we took it back to the dealer who programmed the new fob and they could not fix it. they said they do not know why but that they'll program for free if we buy another fob.

what should i do? it works fine before and i feel it it is not our fault they programmed the new fob but messed up the old one. suggestions?

thanks all!