Good news! Looks like we have been assigned a car!
After encouraging messages from
@Dunstan and
@jfrancis, I bit the bullet and returned to the Tesla chat. The initial response, for the second week running, was: "We don't yet have a vehicle matched up to your order. As soon as we do we will be in touch to advise next steps." I persisted - the order was placed in early May, the end of June (the apparent delivery date) is only a fortnight away, getting a bit concerned, blah blah blah - and chap (eventually) said he would liaise "with our leasing team" and would update us by email.
An hour or so back, my wife received an email to say that "I have rectified your account and you are now matched to a vehicle for delivery this month! The team will be in touch in the next few days to confirm a date for collection from Bristol as this will be the quickest way of getting your car."
I'm so glad I queried this as it does sound like something wasn't quite right. I will now be checking my wife's mobile even more frequently than before for the magic delivery text!
Thanks for your support, lovely people. Progress, at last!