This has to be the worst customer service I have experienced - they simply won't respond! Many of the keys on my brand-new keyboard stopped working immediately after starting to use it. Looking at forum messages, it is clear that this is a common problem and not specific to me. After a long time debating the issue with Logitech Customer Support, they sent me out a new one: it had exactly the same problem! I know it is a problem with the product and not my device, because I have tested it on multiple devices. For 6 months now I have been trying to get a refund, but am being stalled and ignored by Logitech Customer Support - despite them actually agreeing to send me a refund, I simply can't get them to actually do this!