You have two separate issues: 1. dealing with the IRS to correct the error and 2. dealing with TurboTax (TT) to get reimbursed for any penalties and interest (you have to pay the tax).
As previously state, let Tax Resources, Inc. (a third party provider) deal with the IRS. At some point, you will have to write a check to the IRS.
Tax Resources, Inc may also be able to help determine if TT did indeed make a mistake. But, don't be surprised to find out it was not a TT mistake, but an input error on your part.
