The only place I ever get paid is at Peanut Labs. Customer Support there really is interested to hear of problems you've had. If you immediately go to Transactions, the one at the top will be the last one you did. Report a problem, but choose Other. That's the only option that allows you to enter text. Curb your anger and just be intelligent and reasonable. Tell them specifically what happened.
Very long screenout with suspiciously survey type questions.
Survey that gets to about 90% and freezes.
etc.
The second example happened to me a week or so ago. I haven't seen it since, although CS didn't tell me that my complaint was the reason, coincidence?
When I report one of the more common first example, I always start by saying that I don't expect the credits and I'm just letting them know. A couple of times I was thanked, and they gave me the credits anyway.
Keep in mind that there are legitimate reasons for someone to have done the actual survey and NOT get credits. If their automated system detects what they feel to be illegitimate responses, the survey may terminate. One thing many surveyors watch is speed of input. If you're going too fast, it may look like "christmas tree" responses.
Good luck. Lately I've been getting 1 or 2 paid daily. Hope that keeps up.