The AOT website remains offline, but I am told (by the AOT manager at BKK) it is due to come back "very soon".
Meanwhile, the AOT limo service is now operating with an entirely new fleet of vehicles.
Every car, every bus, all brand new, lined up in neat rows of identical Toyota, Isuzu, Mercedes, with sequentially numbered licence plates.
The price for a Toyota Camry has gone up from ฿1200 to ฿1300. A small increase for what remains the best car service at BKK.
I don't know why they had to cancel existing bookings while this contract transition occurred. Whatever that change was, they surely knew it was coming and must have known what the new prices were going to be. After all, you don't buy several million dollars worth of brand new premium vehicles overnight.
As badly as that was handled, they are back and still the best.
I booked one of the other airport limo services after AOT cancelled my bookings. I won't name them because of the very strict Thai defamation laws, but they all suffer the same problem.
As well as not waiting in the place they specified, leaving me walking around for a while, they had no uniform (so once I found the sign with my name on I had no clue which of the nearby crowd of people was the operator), a mildly rude attitude, an awful website (especially the farcical payment process) and they told me it would take 20 minutes to bring the car up.
Twenty minutes sounds over the top to me, but the reason is that (as far as I know) only AOT are permitted to park right at the terminal building.
This is why AOT is by far the best and most convenient service, now that this contract handover is done.
I can walk out of the arrivals hall, be greeted by courteous uniformed staff in the designated location, walk 20 steps straight into a brand-new, perfectly clean (and pleasant-smelling) car, and be driven smoothly and safely to my destination with no uncertainty, no payment hassle, and total confidence they will be on-time to pick me up for my return journey. You'll be halfway into the city by the time the other services pull their car round for you.
They made this contract handover awkward when it shouldn't have been, but it seems the new iteration of the service is still a fair price and right now every vehicle is 5 days old.