I used to be a Utility Warehouse (UW!) gas and electric customer as well as taking phone line/broadband with them. I now just take phone line/broadband as their gas and electric (especially their electric) has, like all 'standard' rates, become uncompetitive compared to the plethora of online deals.
The UW phone line/broadband remains an unbeatable deal for us as we are Sainsburys shoppers (groceries and petrol/diesel). We simply use the 5% UW cashback card for these purchases instead of the usual bank debit card. Taking into account occasional spend at the various other UW cashback partners, our discount tends to be approx £20 per month, leaving a net bill to pay of approx. £3.50! That's for phone line rental, up to 24mb broadband with 40gg monthly download limit and unlimited weeken calls (including 0845/0870).
Fact is, any household who regularly shop at Sainsburys should at least look into taking the phone/broadband product from UW and weigh up if they would be paying less with UW than anywhere else. We certainly are. Gas and electric is another matter, though.
PS An unexpected advantage of the UW cashback card is that it makes Ryanair flights cheaper on account of it being exempt from the £5 per person each way booking fee! We haven't taken advantage of this yet but hope to when our finnaces much improve shortly.
PPS UW certainly IS on the switching sites for gas and electric but tends to be way down the best buys list so easily missed, lol!