I did a couple surveys on freedigitalmoney.com just to play around and get some bitcoins, but it's never payed out, nor did anything appear in 'payments' on their site. There were of course a bunch of surveys I didn't qualify for, but I completed two or three. Very annoying.
I've tried it (multiple survey links) and one other survey site, both were either buggy or scams which did not pay out.
When you don't get credit for completing an offer like this, the fastest way to get the problem resolved is use the button or link at the top right of the website to get help and request credit for the offer. It is best if you have evidence that you completed it such as a screenshot or confirmation email. If you have any questions or run into any difficulties, please email me using the email address shown on the bottom of the website.
We work with hundreds of different advertisers who provide these offers. And some of the offers have problems sometimes. But we always work out the problems that customers bring to our attention.