Not only should you go to his Broker but along with the buyer you should let Google, Trulia, Zillow and all the places where he post know just how dishonest he is. Then contact a Lawyer and sue the Agent and the Broker as they has a fiduciary duty to present all offers to you the seller to make your own decision not theirs. Its a shame that we still have an industry full of crooks when the CFPB was formed to help weed them out.
Lowell E. Sterling
The Federal Savings Bank