Square footage discrepancy

[Susan Robinson]

Hello all, first time home buyer here and recently went under contract on a single family in one of the hottest markets / areas in the country.  Despite asking for only a two day inspection period due to only seeing the house on video before making the offer , The sellers counter was zero inspection, which I accepted.  After appraisal i found out the house is about 300 square feet less than advertised.   I am aware it’s the buyers responsibility in this case to to due diligence but they wouldn’t allow me in the house to do a quick inspection.  It seems it was clearly intentional false advertising am looking for any advice on how to proceed?   thank you