Just to pick up on my moans in this thread (and elsewhere), yesterday via chat I finally got a Tesla rep to "rectify" an unspecified problem with our account (we're leasing via the NHS) - and today we finally had a text to confirm that we have been matched to a vehicle! Last week when I asked, we were told that no vehicle had been assigned and that we should just wait for further information. I'm not sure what the problem was in the end (or whether Tesla or the fleet company were at fault), but I shudder to think what might have happened if we'd done nothing...
I'm not sure if it's that Tesla don't like you engaging directly with them if it's a salary sacrifice lease order, or if the resistance comes from the fleet company (who flatly denied last week that we still hadn't been assigned a car, even though they conceded that communication comes firstly to the customer...!), but anyway. I'll just note here that, if you're getting as close to the estimated delivery date as we were, and you still haven't had the text saying you've been assigned a car, my recommendation is to keep (politely) asking Tesla to sort it out.
Also, although the lease company (VW) ballsed-up the supercharger referral, the fleet company (Knowles Fleet) have said that VW "have agreed to pass on a credit for the supercharger miles" (whatever that means). I say this in case anyone has similar problems and don't have any luck with Tesla retrospectively adding the supercharger miles if the fleet/lease company forget to use the code you provided.