Shoestring - I'm very surprised at their response... Is this a recent model that you bought? Would it have been available over 12months ago?
Personally, I wouldn't accept that .... assuming that the fault is with the product & not caused by you, then you should try to get a replacement... National Consumer Agency web site has letter templates for such complaints, put it in writing all the information, keep it specific & go back in with the letter and product. No harm in ringing national consumer agency either to get their advice...
Also, have another look around for the receipt - you never know - it may turn up!