These are pretty serious accusations. Do you have any details to share? Was your report accepted? How long have you waited for a response?
I have done many, many shops for IPSOS on both platforms, including that one formerly known as GFK, and I have been paid in a timely manner as recently as this week for shops done last week.
I also don't understand this immediacy to jump to the "THEY STOLE MY REPORT" conclusion (not just you, it happens rather frequently). Doesn't that seem like a rather inefficient long-term business model to you? I'm not saying it NEVER happens because anything could happen, but you'd think it was some rampant issue to read some of these posts.
Come to think of it, people are more likely to believe "This company will pay me $500 to buy gift cards/cash checks/go to Western Union" than to believe that this mass report-stealing conspiracy is VERY unlikely.
My two cents.