UPDATE - out of the blue, yesterday afternoon I spotted two Openreach vans (driver of one had parked in a street near my home, and got into the other van before I could speak to either driver)...
Good news is that they fixed line #2, so by 17:30 both lines were active again.
Bad news is that at about 10:30 this morning, line #1
(in use for over 3 years, not 2 months), has lost dialtone and broadband.
Two Openreach vans within 200m of home. First was to fix a problem in my street, second was to fix a problem for someone in one of the blocks of flats.
Appointment for someone from Openreach to reconnect line #1 is Thursday, 02/04
If you run a business, have a second ISP and backup web hosting...