Sorry that it's taken me so long to write this update but I've had a bad cold for almost a week, so today has been the first time I've felt up to even touching my PC. I didn't want to give my thumbs up until I had actual confirmed that my replacement K95 RGB is in full working order.
My head is still a little fuzzy so the dates may not be 100% but if my memory serves me correctly, I got an update to my ticket saying that I was getting an RGB, less than 24 hours after Greybeard said he'd put in a good word. If it wasn't for the fact Corsair received the faulty K95 just before a bank holiday weekend, everything would have been very quick. If I was to nitpick, I'd say it would have been great if I had been updated when the RMA ticket reached each of the various stages (e.g. item received at RMA centre). Overall the service I received was excellent (second only to Dell's, which should be taken as the high praise that it's intended to be).
Greybeard,
Thanks for your help. I've seen you help users on several other forums and you really do a great job.