Called multiple times, but never left a message? I'd be happy to answer their survey but they need to identify themselves, I don't answer if I don't know who it is.
I was getting two calls a day from this number. Then it occurred to me to call the number back. When I did, a recorded message told me that to add my number to their Do Not Call List, go to http://www.mysurveycontrol.com.
Why they couldn't find a way to have that an option over the phone, I do not know...