Unfortunately, what you are describing is a very common situation. Often times, the reason for this is because banks make more money by foreclosing on you rather than if they granted you a loan modification.
In regard to the $15k you are behind, you are most likely already on the foreclosure track. If you do not receive a loan modification, they will most likely try a non-judicial foreclosure and you would need to cure that amount to avoid the foreclosure. Very rarely will a bank accept a cure payment for an amount that large over time. Especially in the instance where the bank might make more money foreclosing.
My suggestion at this point is to contact a skilled bankruptcy and foreclosure attorney. You should get counsel as to your rights under foreclosure and bankruptcy laws and to see how you can resolve this situation in the most economically beneficial way.
This answer does not constitute legal advice and no attorney-client relationship is formed through this answer. If you wish to have a free consultation as to your question and my answer, please contact me at your soonest convenience.