tammy2 said:Instead of talking to company talk to the attorney and ask him what happened.
It is very difficult to get the answer the USCIS. You need to involve your attorney and he should go through the AILA liaison. If you do not have one talk to some good attorney who is member of AILA. Also you can involve your senator/ Congressman.
If company has revoked your I-140 simply giving the new employment letter with statement that earlier letter was an error may resolve the problem. Try gets date they sent revocation letter.
It is very difficult to understand why the company would revoke I-140 for their own employee if everything is fine workwise. It is either USCIS mistake and you have to talk to the attorney (as per tammy2' suggestion), or there is some hidden story behind it.