What's happened to Hertz 24/7 in London?

There used to be quite a few locations in my area (NW6) within walking distance, but I tried to book a car today and found every location within 2-3 miles of me has vanished.

In fact, looking at the map of locations I would say 2/3 to 3/4 of all the London location have disappeared. Only a handful of Central London locations are left, although all the B&Q and Costco ones seem to still be there.

I last used them around 2 months ago and there was no problem finding cars at all then!

Are they shutting down 24/7 in London or is this some kind of temporary glitch?