Thank you very much, now resolved!
Carphone Warehouse complaints dept phoned me this morning but were as intransigent as ever, so told them I would see them in court, and make sure the media was aware of their attitude - I decided to contact Vodaphone again.
Vodaphone were unaware of this Carphone Warehouse practice, and as my contract is really with them they were happy to cancel and made it clear to me that they were not part of this deception.
I then had a call at home from Carphone Warehouse to acknowledge that I was upset, and that as an "act of good faith" they would cancel the contract. My husband took the call and informed them that Vodaphone had already done it and were surprised that the CPW had this 'law' on Vodaphone contracts.
Hopefully I have done CPW some damage!
I appreciate in the great scheme of things my problem isn't a major one, but I was getting so stressed as I couldn't see a way out of it.
Thanks again for the advice