Just wanting some advice on something I've just become aware of.

I bought an iPhone the other day from an O2 Store on PAYG. When I was
in the store I discussed with the salesperson that I already have a
contract, so I don't really need the PAYG SIM until the contract
finishes in December.

Just checking my receipts tonight and noticed that I was charged for a
£10 top-up on my receipt when I bought the phone, this is on top of
the value of the phone itself.

I now have 2 problems:
1) I was charged for something without my permission (can they argue
that I paid, so I agreed to the sale?)
2) The small print of the iPhone SIM is that I get 12 months free Web
and WiFi from when the SIM is activated. Activation is done by topping
up the SIM (so it was activated in the store without my permission)

Has anyone else had this happen and if so is it easily resolved. I
want the card to not be activated until Dec. as each month it is
active and not used, it is effectively £10 wasted (that's how much O2
say the Web&WiFi Bolt on will cost) so in total it will really cost me
£60.