Wow. I went to use my Kindle this evening only to find the screen frozen. A quick Google showed this was a problem with a small number of Kindles.
Went onto the Amazon customer service page, clicked a few buttons to say my Kindle (bought by my wife) had a fault. I was advised to supply my contact number and click the phone-me button, and someone did, immediately, at 11’o’clock at night!
Within a few minutes I was advised a replacement would be with me in a couple of days, and asked to return the faulty one in the same box with a label I could download from the link in the confirmation email.
I have never experienced such an easy and convenient returns process from any other company.