It’s nonsense to suggest that there is some sort of manual checking between Openreach and the ISP regarding job completion , there is no person calling another person and asking the installer’ how did that go , can I close this off ‘ ..it’s an automated system, and contrary to the post here , the error is more likely the OR tech incorrectly booking of a job as completed, as this would would progress the automated cessation of the copper based service , as opposed to BT , completely unprompted , entering systems (why would they do this , no one has brought anything to their attention) and override the automation and manually progress the cessation.
Ofcom requires mist if these systems to be completely hands off , that way , every provider has the same automation/systems so ‘BT’ have no advantage in using historical pathways to put BT customers ahead of any other providers customers…..even in cases like this where it’s BT and no other provider , the Openreach functions and BT functions are linked by IT systems not personnel.
Like @licquorice I can't understand why you did not get the fibre installed and just needed to wait couple of days for BT to send you the SH2 and then all you had to do was connect the hub to get internet
Were you changing providers as well as upgrading? If so then that will be why the old service stopped as it would have had a termination date. No provider will just let it run if you are leaving.