Of course they're trying their luck... you should have gone in 10% below, and put it on paper. Then they have to countersign it or reject it outright.
Actually come to think of it, make the agent do some work for their commission. Go in, sign an OTP at 10% off the advertised price, the agent is obligated to present it to the owner, they might change their tune when its in paper and would be binding on both parties if signed.