I've just been reading the post by Lottie Lou. I have just switched my sim card to a new cheaper deal. The company is called Giff Gaff. Now before anyone starts jumping up and down, i don't work for this company or benefit in any way for putting this on here. To use their sim card your phone needs to be unlocked or on the o2 network. The prices are good if you are looking for a cheap pay as you go sim. Because they use the o2 network the coverage is good and i've had no problems so far. You can choose to top up your phone and be charged 10p per minute for calls and 6p for texts or buy one of the goody bags. I use the £10 a month goody bag, that gives me 250 minutes unlimited texts (both to any network) and unlimited internet. Quite a good deal! Other goody bags are available at different costs. Check out the web site.