eventually turned up nearly an hour after the end of their appointment time window and swapped their modem
which the man said was old enough to have come from an archeological dig. However the problem did not go away.
I have two phone lines so my ISP can dial into my router via line two and poke around inside while it is connected to the separate broadband line. Everything was working except that no data was coming down the phone line. The Openreach guy agreed and put in a lot of effort getting things checked out upstream all to no avail. I don’t really know what is planned next. Put broadband on my second phone line too looks like an attractive option at the moment.