you are within your rights to collect the ring you have already paid for at the agreed price,there are a few options open to you here, you can report them to trading standards, (tell them this, see what there reaction is) tell them they have legal obligation to supply goods as agreed in the signed contract, or your within your rights to get a full refund, if they refuse a refund back to your card, phone up card company and they will be able to claim it for you, however as i said if you really want the ring as per agreement , ask them for number of head office and tell them you are going to make an official complaint of non compliance with a legally binding contract, hope this helps.(if all else fails go to your c.a.b, but i dont think it will get that far)