Ah if the warranty is 3 years and they are not honouring it by offering a repair or replacement do the following if you are prepared to do a bit of corresponding:
Write to them at their uk address offering to send them the board which is under warranty and request a repair or replacement
If you have no joy after two weeks write a second time explaining that you are bitterly disappointed and the situation is unfair, explain if you do not receive a satisfactory reply, repair, replacement or full refund by (two weeks from this moment) you will have no choice other than to claim via small claim and complain to trading standards in the uk
If after two weeks you receive no joy send the a copy of your last letter with a blank n1 small claims form explaining you will issue court proceedings in two weeks time which will unnecessarily increase the fees they will need to pay.
I think they will refund you
http://www.howtotakesomeonetocourt.info/joomla/small-claims-court-forms-ex50.html