People who had their account banned in the last few days before payment may be more likely to feel victimized, and therefore more likely to answer a poll to express their grievance.
That's probably true, and in hindsight it's exactly why polls (and statistics in general) are so difficult. Thank you (and also robryk) for pointing that out!
It's why voluntary polls are meaningless. A true random poll would not have this bias.
People who were banned are probably pissed off and chose 4days.