Further to New Judge's excellent response, can I just point out that it is the RETAILER that must put things right. The RETAILER must repair / replace / refund under the Sale of goods act, and if they try to tell you otherwise they are just fobbing you off. Any guarantee offered by the manufacturer is in addition to your legal rights and you can use it if you wish, but you don't have to. You can insist that the RETAILER sorts it out for you.
I agree with the advice to ask for a refund, mention the Sale of Goods Act, and the Small Claims court if necessary. This will usually get you what you want with little fuss.