I thought that is what happened to us, too (different amounts but the same issue,) and I FINALLY got through to the IRS and they told me that the last portion came to us in a CHECK. Since I had never gotten any IRS form that told us the total, I didn't remember the check. But I went back to our bank statement and found that it was deposited on about the day they said we received it. Is it possible that you actually DID receive the last $1400 in some other form? It is hard to get through to them, but try calling the number on the notice 4 or 5 times a day, and you will eventually get through. They will know what they sent you. If you really only got $4200, then you filled out the form correctly.
