Oh yes I have, but not as a customer. As a creator.
I uploaded one of my bonus chapters for Bloodroot to their KDP. Not long after, I find out they rejected and blocked it. I figured that eh, it's probably because there's dicks in it. Can't get away everytime.
But no. That's apaprently not it. Because a couple days later I get an email saying they have SUSPENDED MY ACCOUNT and that I can't upload anything more to KDP unless I send them an email with a specific line copypasted, saying I will not upload content that is against their regulations blah blah. The reason? "We see that the content you uploaded is not yours and is available on the web".
What the fuck? No. It's an exclusive bonus chapter that is not available for free reading, and I am the original creator of both the uploaded chapter and the original series. I send them an email thoroughly explaining this. Then I copypaste the dumbass line they wanted.
I get an email where they respond to absolutely nothing of what I explained and simply say the suspension has been lifted and that if I "break the rules again" I could be suspended for good.