Consulting an attorney is good but you need a knowledgeable attorney, the attorney generals office is a great place to start as they would know an attorney qualified to handle this technical a case. (Not all attorneys are created equal). Getting the copies of both appraisals is very important, you will have to document your case and the source of the "distorted" valuation if that's the case.
Another factor here is the "Macro/Micro" effect of the different economies at the past origination and the current economy which has led you to today circumstances. When you first originated your debt the country was at nearly totally employed population, today so many people are working three part time jobs to meet their debt obligations. None of us had a crystal ball but the original appraiser would have had to collect sales data to support their opinion, it almost sounds like the sales data at the time was "inflated". None of us can say what originated the source of this opinion.
Good Luck and please keep us posted.