+ 1 here as well. If you have the survey number, that's helpful, but just give them the date and time, describe what happened, and request the appropriate amount of points. I usually try to give them a description of the survey so there's no question which one was problematic. I almost always get credit without the need for any followup.

I once wrote and asked them to explain how, after trying to answer surveys the moment they hit my inbox, I was still being told that the opportunity had expired. FWIW, the reply was that they often send out the same survey in multiple waves, so if I'm in the fifth or sixth group to receive the survey, it may already have been filled by people in the preceding four groups.