Hmm a few reasons
customer service was fine the first time or 2nd that i had a problem
then after i had a fault where my IP would vanish and i couldn't connect to the internet at all the customer service team didn't have a clue they sent me out a new router even though me telling them it would most likely a network problem on their end yet they disagreed with me and about an hour later it started working again on its own the same router same old IP ect.
i phoned again and got through to another person and they confirmed it was a network problem and they cancelled sending me a new router but i got one anyways
i had the same problem about 2 months later and they suggested to send me another new router even after explaining what happen the last time
it was like speaking to a wall so i just left it and about 2-3hrs late my ip returned and all things where good again.
the big problem was these disconnects where during while i was uploading projects or having skype calls with clients very annoying
but yeah after like 12 a months the price suddenly hiked up to £50 a month and thinking about the customer service being naff for the price i was paying, i decided just to join BT
£62 for infinity 2 unlimited weekend calls + my mobile with the same number unlimited calls texts and 20gb of data (works with tethering) and 125 quid mastercard.
Not really a bad deal considering.