So after ordering my car at the beginning of August and gradually realising the "September" estimated delivery was somewhat optimistic I started browsing this forum. It's been nice to learn I'm not alone in my frustration and there are a lot of people in the same boat (or hopefully their cars are in the same boat).
Earlier this week I started getting the SC VINs appear in my account (and then promptly disappear again), and about the same time I noticed the Existing Inventory option for the Model 3 disappeared too. Up to that point the Existing Inventory had sporadically shown a handful of cars available, or when none were available it was an empty list.
This could all be coincidence but as I haven't got a model 3 to drive around I have nothing better to do it made me wonder whether there was some link. I can only assume a car was assigned to my account and then for some reason only known to Tesla UK they unassigned it. What happened to this car? I'm wondering if these unassigned cars are now in effect Inventory and therefore they have had to remove the Existing Inventory link until they complete their assignment?