I would be extremely surprised (and concerned) if ISPs were not informed.
I see planned engineering work all the time, affecting anything from a few lines, up to hundreds of lines and more. For the most part, PEWs do not affect end users or if they do, they result in a very brief loss of disconnection in the early hours. I think is why nearly all ISPs do not report this work.
I am not aware of a single ISP that would automatically report every single planned engineering work affecting specific circuits to end users. There are a variety of sources of PEW and I think it's quite a big task for any ISP to be able to input the multiple daily updates and then output this as meaningful and useful information for end users.
I can assure you that according to Zen, they were not informed of this planned engineering work and it has never appeared on any of the PEW status reporting sites. Indeed, the very nice guys that I spoke to on site said that there should only be one disconnection per line. When I chatted to them a few days later, they admitted that they had found aluminium in the old cabinet that was giving them a lot of break of service issues ( which, in turn, meant that they were receiving a lot of complaints about BB disconnections from my neighbours).
I wasn't suggesting that the ISP should inform end users but, in my view, as I had raised an issue with them, I would have expected them to contact BTOR. All Zen would say is 'we do not have many customers on your exchange.'