Happy funding, Rudi
Ask your realtor to provide at least 3 comps in the same neighborhood where your home is located that have sold and closed in the last 3 to 6 months. It only takes one comp to raise the question, however the more you have the better your claim. Unless you can provide solid proof the numbers are wrong most appraisers will stand with the original amount. As for loosing the buyer, who knows? They all are skittish these days.