I RECEIVED A LETTER FROM THE IRS/STATE
TurboTax does not receive any information from the IRS or your state after your return was filed, so no one at TurboTax knows about a letter you received from the IRS or the state.
If you purchased the add-on Audit Defense product, their contact info is shown low down in the table at the first link that @xmasbaby0 provided above. Even if you didn't purchase the add-on Audit Defense product, you can still get free help from TurboTax's free Audit Support Center. At that same link, scroll way down to the bottom of the table, and you will see the special phone number to use to contact TurboTax.