The best place to complain is to Microsoft for ending Win 7 support. The last thing Turbotax needs is media reports of their customers being hacked and data stolen from their tax returns. For this reason. TT simply cannot afford to continue to install their products on an unsupported operating system.
The thing to do is go to Microsoft. XP users got an extra year of support when that ended because so many users complained to them about ending XP support. We have here the same situation. MS has ended support for Win 7 so ALL software vendors have to stop supporting it.