personally, I would do three things as this is getting "long in the tooth" and I would be frustrated as well
1) first, confirm that you had a positive amount on Line 29 of Form 8962. if it is not positive, there is no adjustment.
2) review your transcript on the IRS website and see if you can see if there is any movement or indication it is under review.
3) call the IRS. what other posters have stated it is easier (somewhat) to get through near the end of the day - so try calling around 6:50 p.m Eastern time.
the 1040-X will take 9-12 months to process, so I wouldn't do that at this time.
https://www.irs.gov/individuals/get-transcript
