After you file

Its been 3 weeks since I received the check. How long does the letter take? I spoke to 2 IRS reps and they are unable to tell me what is causing the discrepancy, only that it exists.

It says W2 or 1099 withholdings change code 806 on the transcript. I had no change and I did a paper amendment only to change the exemption number and nothing else at all.

Is it possible someone got a hold of the outgoing amendment in the mail and altered it?