Just wanted to follow up with my experience. The 843 failed, they rejected it, completely disregarding that the form is can be for requesting a refund or for abatement of taxes owed. They acted like I was requesting abatement of taxes, not understanding at all that I was requesting obviously excess withholding to be refunded.
I wound up paying a new accountant at a big tax firm in the neighborhood to handle the situation. They filed an amended return and claimed the excess witholding on line 10 of Schedule 3 (Form 1040). IRS has accepted this but I still haven't received my refund so, we're cruising well over than a year for resolution here. Pretty insane how much onus there is on the taxpayer to recoup something as simple as a limit being exceeded for a single thing.
