Yey! I've got the refund. And the company have learned something!
"According to your steps, we used kindle paperwhite 3 to operate, and we understanded what you mean. We have reflected this problem to our supplier and will improve product performance for more customers. In order to allow customers to read when the product is standing, so we launched the product that was recommended for you in our store.
By the way, There is no product on the market that can satisfy the horizontal screen mode of Kindle paperwhite, which is the limitation of kindle paperwhite. We are so sorry for the inconvenience, we will arrange to refund to you. If interested, We can provide a upside down flip for free to experience. Thank you for your detailed answer.
Have a nice day."
Not sure what they mean about providing an upside down flip for free. What's 'an upside down flip'? Sounds like what I already have.