This is the main reason I decided to try another ISP in a couple of weeks. I've had one too many of these outages in the last 18 months, which is a shame as the service otherwise has been great.
I switched over to CityFibre when I moved to Zen. I think one or two of the outages have been related to CF but the majority seem to revolve around planned maintenance with Zen. I will find out if I was right in the next 12 months. I am in the fortunate position of having access to Open reach And Virgin fibre options as well but I'm staying with CF for now