I haven't heard of the account page showing next billing dates in the past--I'd contact billing. If there's a wider issue which is persisting I'll post an update.
It's not just the billing date showing in the past, it's the fact that it's showing in the past BECAUSE I HAVE NOT BEEN BILLED. And I'm obviously not the only one experiencing this:
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Looks like something your billing department needs to look into ASAP. I'll probably call also, I don't want my account suspended for non-payment because your billing is jacked up.