Noted a post today from "jelv" which says quite a lot for Zen's technical support service.
Issue reported:
https://forum.kitz.co.uk/index.php/topic,26888.msg450950.html#msg450950Issue resolved:
https://forum.kitz.co.uk/index.php/topic,26888.msg450962.html#msg450962The time scale between reporting and resolution in this case can't be faulted!
Ironically I'am on my last day with Zen BB FTTC & phone service, FTTP install with BT due tomorrow.
Was tempted away from Zen to BT with their current FTTP + phone offer on 18 month contract, due to a number of install delays, all be it with OR which would likely have occured with any ISP, hopefully the install will actually happen tomorrow.

As always, will certainly review my options for next contract period and Zen will likely still be high on my list.
Edit: Typo correction.