Agreed with the OP here in that Virgin (formerly NTL) were reliable most of the time. Except during heatwaves. Their repeater boxes that you see on pavements are dark green in colour, and dark colours absorb heat more so than lighter colours, so they knacker up in heatwaves.
As for bill increases, I was paying £25/month on NTL's middle broadband tarif from 2002 to 2006, then when Virgin took over, I noticed that friends and family were paying £20/month for the same service. So I called Virgin to query this, why I haven't been moved to £20? They said that I was on an old contract but they could move me over, so I did. It was probably a mistake on my part in the end, because the £25 was fixed from 2002-2006, but the new £20 rate was only fixed for a couple of years, then it started going up by about a quid per year. In 2018, I was paying £34/month, and in 2019, Virgin said that it will be going up to £38/month. I could ignore yearly increases of £1, but £4 was too much to ignore.
Next up was to cancel with Virgin, which was an obstacle course on the phone as they try every trick to keep your custom but managed it ok in the end. It made cancelling with AOL seem like a walk in the park
Then I went with ADSL (or VDSL I think it's called now?)-based providers. Once you're with ADSL providers (as opposed to cable), you can easily switch once a year to keep the monthly rate at around £25.
Now though, I have switched infrastructures once again to 5G and I pay £17/month for unlimited (true unlimited) data with Three. Currently getting 450mbit down, 50mbit up with an ms of 42, but on a good day (normally late evening), I can get 1.1gbit.