I purchased HiFiMan He-4xx in September this year. After a month or so thee product has shown issues. Rattle in right earcup. I opened a ticked on 19th of November. I was told no new batch is available for replacement (which is weird as there is another drop of the product, but exclusive to new orders, not existing warranty replacement - quite shocking). I was given the option of 20 USD coupon (laughable) or a refund. I paid customs fee on a product already so that option means a loss on my side. I finally decided to go for full refund. I informed the support about my choice. Gave them the address. 12 days passed. Nothing. I wanted to decide to buy Panda TTHX here, however I need the refund to be processed first. It is quite abysmal customer experience if you ask me. Now, has any of you had similar experience in this regard?