Here's my little suggestion and it's worked for me. Email and then TWEET the company. It's public, and in a professional way you can ask when you will be paid out. They will be a little more likely to respond to you as opposed to ignoring it and having all your followers and anyone who searches the hashtag (put the hashtag!).
Very food point!! This is something I have done before...especially on public sites...what I do is privately first and give them time to respond...then I go public
. Not for this type of thing though....
That said, I do agree that it is unwise to continue working if previous "due" payment has not been made. Its not all about the money...but it is all about the money, if you get what I am saying
. The reason we work is because we want to make money, therefore if we are doing the work but not getting the pay, we should do something different!