Thanks, Rayna ... yes, you're right. Luckily, I've a nephew who lives locally and, like Keith, being an IT specialist, he fixed things in 5 minutes' flat, yesterday afternoon.
Actually, I'd been trying to contact him since Friday to no avail ... only to learn from his dad (my brother) that Stuart had given up his landline phone in favour of a mobile, as he's more often out than at home. So at least I know how to get in touch with him more easily in the event of a recurrence.
Enjoy your holiday.