I have contested appraisal and won, and contested appraisals and lost.
You need comps......that have sold within the last 6 months and with in a mile.
There is no gurantee that you will win, but if you try to get cute, you will definitely lose. Be sure your comps are the best available.
You have a few options. #1 Ask your loan officer the same question. He should be able to help you get answers. #2 Contact Alan Openshaw, the Broker who replied to your question or any other or #3 Build your own case by finding comparable properties on Trulia that substantiates your claim.
Kevin D. Jamison
You can always change lenders too if this lender doesn't want to toss out the appraisal. (If you are doing an FHA loan, the appraisal can't be "tossed out".)