Personally, I don't do surveys. But here are my thoughts: WGT probably needs to revise contracts/agreements with the survey companies. All surveys should allow you to finish them and get credits. The survey company can throw the results in the trash if they need to based on the demographic profile they are looking for. But if the WGT member took the time and made the effort to do the survey he/she should be rewarded.
On the other hand, surveys are worthless to the marketing company if the same person takes them over and over. WGT should set up a system to limit surveys to one each per member, per offering company.
Otherwise, we're all like laboratory mice being sent through the same maze over and over, each of us nibbling at crumbs to get a small reward at the end.