Claiming a dependent

Hi All,

I usually claim my son on my taxes, he is a full time student and works (not enough to change dependent status).  This year he did his own taxes and did not check "someone can claim me" and submitted his taxes.  I am doing my taxes now and have him as a dependent.  however, when i submit my taxes, it is declined because of the former reason. As far as i can tell, no one in the IRS is answering phones and I'm stuck.  He did file an amendment, but I have no idea when that will be processed and if it will even fix it.

Has anyone had this issue before and how did you solve it?

Thanks in advance.