I personally find it repulsive that you think you should be given such a personal benefit because your group had a problem. If it were you alone you'd recognize how truly absurd a request being given silver medallion status for one cancelled flight is.

I understand you think you helped supply delta with lots of business for a group booking but a one time traveling in a group to a music competition isn't going to make delta desperate enough for your revenue to cave into such a bizarre demand.

Take your seventy five dollars and use it towards another flight or find another airline. I hear United has exemplary customer service.