DD the nice approach doesn't work. I used to work in the call centre for a large profit hungry, shite on your customers mobile phone retail company. Don't waste your time calling into a store or call centre go direct to the shop and play hell with them. Go in early, They will want you out of the shop before it gets busy. Store manager should be able to sort something out. Tell them you were mis sold. The sales rep stated the phone was the tits right and it doesn't work for you at all. The lack of a signed contract is interesting. If the sale was over the phone/internet you may have been stuck after the cooling off (distance selling rules) however in branch they have to have a signed contract to send to the network and keep for their records. If they don't have this then I think this is your chance to get out of the contract. As mentioned above an "upgrade" is any change to your contract terms, regardless of you being in or out of contract. eg you can upgrade in month 19 of a 18month contract. Suggest you be firm and lay out all your demands. Refuse to speak to anyone on the phone and deal with the manager only.
Good luck,
Ps I hate phone companies and their contracts! bastids.
2hottie.