The survey pin locations are memorialized in your recorded deed at the Court house.  They are nice to have for the surveyor but completely unnecessary for the survey.  Still I would do as Army said and complain to their main office.  My guess is that they will replace them.  The road repair crews are generally private enterprises who won a government contract.  They are going to do as little as possible so I'm not surprised that they said they won't replace them.  Talk to DOT and see if they will make them do so.