OP if it makes you feel any better (it likely wont, lol), this is not a "Tesla UK" issue, it isa "Tesla" issue.v They are like that in the US as well. I have sent emails asking a question to the referral team (as an example) and gotten an answer like 3-4 WEEKS later, with the email starting with "sorry for the delay in the response...."
I would normally chalk this up to tesla being a car company aimed at the "new way younger people communicate" (not having adequate phone support, etc), but they also dont respond very well to emails. I really believe its a product of the fact that tesla is just now trying to figure out how to be profitable, and the people that seem to get cut the first are the ones on the "front lines" answering phones, emails etc.
In Tesla's "perfect world" you would:
1. Place your oder online, with no human interaction whatsoever
2. Wait patiently for someone to email / text you, telling you when and where you will need to arrive to pick up the car / or when and where they will be delivering the car (with no rescheduling by you, but possible rescheduling by them, via text / email.
3. Show up to pick up the car, finally meet a human, sign the papers taking ownership of the car first, then go out and be given a cursory instruction on the basics of the car with a note that "the manual is in the car on the touch screen.
4. You drive off, read the manual and dont need any after care support
5. Since the car is supposed to be low maintenance, you do not contact anyone unless there is a maintenance issue
6. If you have a maintenance issue, you make an appointment, in the app, without talking to a human
7. You show up, drop car off, take your rideshare credits and get a text message when they have completed whatever work required.
In my opinion, thats tesla's perfect world, and its the world that many millenials (and younger) would prefer, but its not the world that many of us with the finances to actually buy these cars prefer. Since tesla is not "working on commission" the sales people are not tripping over themselves to help you, like a regular "dealership" . You cant just drive down to the "dealership" and talk to someone about a problem with your car like you can at a traditional car dealer. You can go to the service center, but they are over worked, and busy.
Even in Tesla's perfect world (my opinion of what they want, anyway), they still dont have enough people for the massive growth they have. They are attempting to go from "niche player" to "major force" in international car manufacturing / delivery. They are doing it, but the service has a long way to go to catch up. Its my opinion that they will never really catch up to what some of us older people want, but that, EVENTUALLY, they will get good enough at the digital parts of the communication that we will accept it as "ok".
If you have questions about car operation / features, much better to read the manual in the car or in the PDF online, and join a car forum (like you did, OP), and read, or ask questions here. Its not a tesla issue that car forums always know more about the car than the "dealers"... the difference is, its easier to go to a regular dealer and have them tell you "I dont know" to something that is known on the forums than it is with tesla