You’ll need to follow the directions in the letter you received to dispute the adjustment. Make sure you follow the instructions exactly, and be aware of whatever time-frame is noted for contesting the decision.
You should try calling the phone number on the letter, but be aware that there may be a significant wait time, if you get through, at all. You can also respond by mail.
See TurboTax Help article I got a letter or notice from the IRS for help in understanding the notice you received. If you don't see your notice listed there, go to the IRS Notice or Letter page for more help.
