Rach shop around, have a look at
http://www.moneysavingexpert.com/ you'll see it's very favourable to switch all sorts of suppliers.
I work on the principle that I'm the customer and therefore I want the best deal for me, companies don't know the meaning of loyalty so why should I be loyal to them. Shopping around is the only way to make sure you're not ripped off these days whatever you're looking for.