I can't believe that many marketers still ignore customers who are dissatisfied. Especially since most of the complaints make their way to social sites. Ignoring them won't make the problem go away, and if the non-responsiveness continues, you may get a tweet with #FAIL attached to it and you'll be part of an elite group (where you don't want to be in) who have failed their customers. This is more of a problem for B-to-C companies than B-to-B, but none the less, you still shouldn't ignore people.