Sorry to hear about your friend's problems. Who handled the loan modification? Washington Mutual went bankrupt in 2008, so it wouldn't have been them. JPMorgan-Chase acquired WaMu's assets afterward, so perhaps they are the ones you are referring to?
Hopefully your friend kept all her documents from the loan modification so she can show what the terms of the agreement actually were, what the amortization schedule is supposed to be and how much is due at any given time. The loan modification documents should be able to tell you this. Hopefully she kept all her other communications with the loan servicer as well, as this could be used to document just what promises were made and when.
This illustrates a key point of any mortgage transaction - always keep all of your paperwork and communications. You never know if you might need them in a dispute with the lender some years down the road.
Unfortunately, loan modifications are at the discretion of the lender and they have a lot of flexibility in the terms they offer. You can either take the terms they offer or they can foreclose. If she obtained her loan modification through the old government Home Affordable Modification Program (HAMP) there were some restrictions on just what lenders could do, but if it was strictly a proprietary modification on the bank's terms, it's a different story. However, the bank is always limited by the original terms of the loan, which set for what sort of penalties or higher interest the bank can charge in the event of a loan delinquency.
It sounds as though your friend may need legal help in sorting this all out - I would suggest that she speak with an attorney specializing in residential real estate matters to see what her options may be.