They know their engineers don't run to time...

[#1]

I keep finding this, as I trawl through the forums, posted by PN staff:
"I just wanted to state that if you are expecting an engineer to arrive to either install or work on a fault with your service and they either haven't arrived during the booked timeslot or if it's getting towards the end of the booked slot and you're worried they might not arrive, please be aware that we need to allow 2 hours after the end of the slot before we are able to chase this up with our suppliers. "
They clearly know that BTO engineers are unreliable. I've just had an engineer fail to turn up today - for the second time. Apparently, BTO cancelled the order.
Bloody rubbish customer service. I don't really care that BTO are most likely the culprits, PN OWN the process, or at least they should. Shoddy.

[#2]

PN may or may not "own the process" but they don't own Openreach who do their own thing regardless.
If you watched BBC Parliament yesterday it would appear that the whole country is dissatisfied with BT Openreach.

[#3]

If BTO OpenReach cancelled the order that wouldn't have happened today and Plusnet should have told you the engineer was cancelled.

[#4]

Well, during a discussion with PN the person at the other end of the chat told me that "BT" cancelled the order (my assumption is that she meant BTO). No notification was sent to me.
PN may not own BTO, but they are the service supplier (i.e. service to me), and as such are responsible for the whole process end-to-end (legally).

[#5]

Have you looked through your tickets see if there is anything before today about the order being cancelled?