I am not taking any chances anyway, i've told em to remove it or they can shove their phones and their contract.
I'd advise that whilst dealing with mobile phone companies you exercise extreme caution. I'd certainly pay the charge and try to claim it back later.
When you sign up with a mobile phone company all of your bill payment history etc is recorded on your credit file.
Once something bad goes on there, believe you me, you will have a torrid time trying to get it removed, and the fact that it doesn't warrant being there holds no sway what so ever.
On 1 occasion I failed to pay an incorrect bill only to resolve the issue the next month and but was already marked up with a missed payment.
Although this pales into insignificance compared to the Water board who gave me a CCJ when I moved into my new house, for not paying the previous occupants bill. This is still on my record 6 years later!! Hate to think what this must have cost me in this time.