Fibre via OpenReach is an engineer install in your house (at least it was with mine), not just the flick of a switch somewhere, hence the charge. I’m sure my charge was much less than that though (although I was on Zen ADSL already so maybe it was a deal), it was an 18 month contract to so might be absorbed into that (if your £155 one was for a rolling monthly contract?). Zen is a bit more expensive in general but the service (and customer service) is very good.
I was curious if the Vodafone (no line rental option) would shake things up but if it’s £28 then it’s just moving a lot of the line rental cost into the service cost so hardly a game changer. I’m also not going to be an early adopter of a new Vodafone service given how much bad press they get for their mobile phone customer service.