You should dispute the bill in writing. As this is an ongoing contract, I would also phone them up to say that I was disputing the bill and would put my reasons for doing this in a letter. I would ask them to confirm that they had marked the bill as disputed at their end if they wanted the contract to continue.

You are only required to pay for what you have agreed. If you have agreed, for example, to pay £30 per month plus the cost of peak time calls, that is what you should pay. Before disputing anything, you need to establish why the bill is higher than you expected. If the reason is simply that you made a lot of chargeable calls, then that is not a reason to dispute the bill.

Hi, I just changed to a 3 phone from vodaphone because they were having a good deal at the time. When I received the bill I nearly fainted, it was much more than they told me (nearly double!), i'm pretty sure that they cant do that, so when I phoned up to complain they told me that it was a charge for the first monthes usage. Well this was the first time I had hear of a "first month charge", is this legal? What can I do if it is'nt?