I had a phone call with an agent who was extremely helpful. I accidentally hung up before the survey. How do I leave them a review?

I will bring  your post to the attention of the Moderators, they can let the agent know that you found him or her extremely helpful.  

I had a phone call with Dan today and accidentally hung up before the survey started.  I would like to compliment him and Turbo Tax for being so helpful and patient with me as we solved a software glitch in my "stock donations to a charitable institution" that locked up the program.  Dan was knowledgeable, understanding and a tribute to your company.  He helped me escape the lockdown and move on to complete the taxes.

You may receive an email asking how helpful the service was but if you don't, don't worry. If Dan is that good, I am sure he has received many complimentary surveys.