Appraisal contains erroneous data

[Kar Sun]

What is the recourse if the appraisal contains data not listed anywhere and the appraiser did not measure the property? 

The source of data is listed but that source has the higher square footage than listed.

The contract has contact clause that has 3 days limit upon the receipt of the appraisal.

Either the buyer accepts lower appraisal and terminates contract or brings more cash to closing to cover for the difference.

I filed an appeal regarding the erroneous data and neither lender nor the appraisal company will give me an answer.

Thanks