Unfortunately when switching to a new provider there needs to be a spare port for you to be switched to. I do think this needs to change though.
You had even more bad luck as the port that you were connected to has been given to someone else, which means it's a case of waiting until either more capacity is added or somone cancels their service.
I don't know that that is so much bad luck as bad management. Switching the other way - from Plusnet to BT - Plusnet kept my acount active until after BT had done their adoption even though I personally gave them 3 weeks notice of the switch over date. And yes, because of the timing, I ended up paying an extra month's rent but that was refunded when they finally closed the account. When I rang up to complain I was told that that was to ensure that my service was maintained if the swap didn't go ahead on time.
Webby I posted a picture below of what address checker shows but I don't understand much of it.
Foxcliffe I don't know but we feel really fed up and lied to. If this scenario will remain a case then they put us in a big trouble.