And so it proved. Apparently, 3 pm is near enough to "morning' for their purposes and they forgot to ring. Then I gave CountryWide a few calls and they managed to persuade the technician to return. He showed at around 5 pm, removed the ISDN modem and tested the line. It worked; my phone line is no longer connected to optic fibre but state-of-the-art copper. He also supplied a patch cable for the ADSL modem. Mine wouldn't reach far enough.
Plugged John's old ADSL modem into the power, the phone line and the uplink port on the 5-port mini-switch. Sandy immediately started collecting the mail - at lightning speed. Had to switch SMTP and DNS servers to get everything going properly. Had to ring work and ask for the IP addresses of Bigpond's DNS servers. Only the boss was still there (and so he should be - he didn't show up until 11:30) but he gave the the IP addresses. He says be a Real Man and configure the modem as a DHCP server.
Anyhow, now I have... Broadband at last!