As fellow users all we can to is refer to the announced coverage, which doesn't add to what you already know. Logically one would think coverage would extend to a replacement board if it uses the same chip set as the ones being replaced...logic does not always work in business, though. Best answer would come from Apple, press the issue with your history. Try contacting the Apple UK, since you talk about cost in pounds, and see what they say. The overall Apple contact information is: http://www.apple.com/contact if the UK source doesn't help.