Legally paid in full vs. deficiency?

[Steven Miata]

I pulled this statement off of this forum: "Also, a little known fact, is the lender could actually report to the credit bureau's as the loan being paid for less or settled for less. If a lender reports the loan on your credit bureau as settled or satisfied, they will have a hardtime going after you for the deficiency. It is always a good idea to pull your credit report a month or two after you close".

My lender reported short sale as " Legally paid in full for less than full balance". Zero Balance.

Now they seek deficiency through collection agency. First collection agency folded, sent it to another, now we are demanding they validate debt. I dont believe Chase has the original promissory note from WAMU to enforce the deficiency. I sent bank a QWR to explain their actions.

Any help or comment?...Thanks.