One of the last ways you can fight foreclosure is to make them produce the note. In many cases the note is sitting in a warehouse somewhere and nobody knows or cares where it is.
I used this to get out of owing on my last cell phone bill after I had already canceled the contract. Didn't have to pay the hundreds of dollars bill because they didn't have the original signed contract that i asked for anymore. Collections couldn't collect either because they are nothing more than a third party interloper and I signed nothing with them either. I don't know all the details on their end but I tried and saved my $$$.