(Edited 2 years later to add that I've moved to Virgin Media because I wanted an upgrade to fibre and they are the only available service in my area. Wish me luck... Would have stuck with XILO otherwise)
I became a Xilo customer after successive screw-ups by two other ISPs.
First, Orange incorrectly handled transferring my account to a new phone line. When they realised their mistake, they said it would take 7-10 working days to put it right, so I cancelled and signed up with Virgin cable who had told me they could have everything up and running within that timeframe.
Fast forward a couple of weeks: Virgin ring up to say I can't receive their service because it would cost them too much to do the wiring, as I live on a main road. I later found out the flat below has Virgin, so obviously their records were incorrect - which lost them a customer.
By this point I was frustrated with the poor level of service I had received from Orange and Virgin - the Indian call centres that both employ are particularly enraging - so I looked into Xilo, who seemed to have built themselves a good reputation for customer service. I was able to call them up and discuss their broadband packages with a genuine English person who actually understood me.
I placed the order and the line was activated on the agreed date (albeit at 9 PM, by which point I was beginning to wonder! ISPs are not in control of this though). Speed is very good and I've since used their online ticketing system once - their replies came back within minutes.
The only disadvantage of Xilo compared to other ISPs is that they don't cover the cost of the ADSL router. You need to purchase this and set it up yourself by following their instructions. But at least they don't supply you with a cheap Netgear router like Orange!
As for why Xilo remains a comparatively small ISP in terms of market share: in my opinion, this is because they are mainly a hosting company, and therefore their website is structured differently to that of other ISPs. This is likely to put prospective customers off. And this is ironic, because the recipe for a good ISP is identical to the recipe for a good hosting company: fast/reliable infrastructure, and good customer support.
If I were ever to need web hosting then Xilo would be the first port of call.
Overall, very happy, and not foreseeing revisiting the ISP question for a long time.
Time With Provider:
Package Name: