The only entity I know of that would fill that bill is the fairness monitor. Even at that point, the fairness monitor's role typically would end at the end of the evaluation and not proceed into the contract award process. So, short of filing a lawsuit, I don't know of anyone you can complain to if the contract isn't implemented the way it was supposed to be.
As I said, in this case the fairness monitor was not assigned. Beyond that, I don't know of any mechanism.