How do I report to Turbotax a number being calculated wrong? Or how can I edit the number myself? It won't let me

@CWS3 Just do not see how this calculation could be incorrect.  

As stated on Line 26 of the Form 8962 -

Net premium tax credit. If line 24 is greater than line 25, subtract line 25 from line 24. Enter the difference here and on Schedule 3 (Form 1040), line 9. If line 24 equals line 25, enter -0-. Stop here. If line 25 is greater than line 24, leave this line blank and continue to line 27

The only other thing to do would be look at a diagnostic file from your tax return.  But that can only be requested by a TurboTax support agent or a TurboTax Tax Expert.  Both of which I am not, since I am not a TurboTax employee.

The only other information available is from the Form 8962 instructions for Line 26 -

Line 26
If line 24 is greater than line 25, subtract line 25 from line 24 and enter the result on line 26. This result is the amount of your PTC that is more than the APTC paid, your net PTC. This amount will reduce the amount of tax you must pay with your tax return or increase your refund. Also enter the amount from line 26 on Schedule 3 (Form 1040), line 9. Skip lines 27 through 29. If line 24 is equal to line 25, enter -0- on line 26 and skip lines 27
through 29.

If you elected the alternative calculation for year of marriage, and line 24 is greater than line 25, enter -0- on line 26 and skip lines 27 through 29.

Does any of the above for Line 26 apply to your situation?