Windfall or stay of execution?

I sent FlexCar, the car rental service that I use instead of owning a car, an email last week. I’d noticed that somehow, my billing had changed from the Advantage 10 (base fee for 10 hours of usage in a month, gives access to cars limited to 7 or 10 hours of use per day, no charge for the hours between 11 PM and 7 AM) to the Standard plan (which charges a flat rate by the hour, does not give access to hour-limited cars, and charges for all hours of the day) without my knowing it.

I asked their billing department how that had happened. If I change my billing I get a confirmation email from FlexCar, so I’m pretty sure I didn’t accidentally switch it.

That change would result in a much larger bill for me, so I was concerned.

I never got a reply to that email, but I did receive my bill this week and the bill shows no charge at all for last month’s use. It also shows no actual use, even though I did, indeed, use FlexCar in the month of October.

I can’t tell if they’re being nice because of a billing error on their end, or if there’s a problem with their billing software and I will, eventually, be charged for October’s use. It kinda feels like a windfall (assuming I was on the Advantage 10 plan, as, um, planned, I would have owed $144.50) but I’m still concerned that they might charge me later.

Hello, FlexCar? Can I get a reply to my original question?

Update: I got a second bill in today’s mail. It explains that there was a billing error, and that my card will be charged. They’re holding off for two days for some reason – they claim it’s for my convenience or something.

Good thing I didn’t spend that money, huh?