Assuming the trouble is with the amp since you don't specify?
My only piece of B&W gear is a pair of headphones. At some point the ear cushions (or whatever they're called) became weirdly sticky, some issue with the leather used by the factory. The headphones were long out of warranty nor had I proof of purchase, but I figured I'd give B&W US a ring anyway. They apologized and actually sent me a new pair of headphones, and I rnailed the old ones back. I had an amazing experience with B&W's customer care.
Were I in a situation like yours I would definitely give them a call.