Recent experience with complaining to e-rewards seems to indicate that they are batching their email responses or something. It is pretty common for me to receive responses to 2-3 complaints submitted over a 2 week period, all within 24 hours.

I complain pretty regularly if there is a significant mismatch between effort and outcome. They always give me a lame excuse about why I may have screened out but I also get something for my trouble about 75% of the time. I vary between asking for more compensation and expressing outrage at how their survey providers are taking advantage of people. Honestly if they stop being so responsive I'll probably stop participating as much.