There is nothing in TurboTax that states what you describe. TurboTax has an accuracy guarantee which basically says if anything on your return was calculated inaccurately, TurboTax will pay any interest and penalties that result from the inaccurate calculation.
The satisfaction guarantee is for 60 days on the CD/download product only. Once you pay for the online product, there is no satisfaction guarantee.
You need to wait and find out why the IRS reduced your refund. The IRS should send you a letter with the reason. There are many things that can cause it almost all of which have nothing to do with the TurboTax
program. See this IRS topic: https://www.irs.gov/taxtopics/tc203
