Believe me, I am VERY unhappy with Ibill right now, but in all fairness:
I just searched through this last weeks worth of credit card rebills in CMI and didn't find any Visa rebills. Only MC and Discover.
And I also didn't find any Visa declines listed.
I also have a theory on the Visa declines others are seeing. It's possible they made it past Ibill's current Visa ban because the decline was already in the works... You know how it usually tries 2 or 3 times, and says something like "rebill declined, will try again on [date]"... Perhaps the declines showing up are simply the ones that were scheduled to retry before Visa was taken out of the system and they just made it through a loophole and went ahead and retried when they were scheduled to.
