Three weeks ago my Macbook Pro's keyboard (with the butterfly design) became completely unusable after 6 months of being mostly unusable.
Not only did the authorized service provider (Apple doesn't have its own presence where I live) take more than a week to get it replaced, they refused to do it under warranty because there were some scratch marks on the side of the laptop.
They told me to contact Apple Support if I wanted to dispute that.
After spending 6 days haggling with Apple Support and being bounced from agent to agent, I was finally told that they cannot replace under the existing Apple Care warranty because of the scratches on the side.
I then asked them to give me, in writing, a note explaining that they were denying me service under warranty for the keyboard issue.
That seems to have done the trick. Two days later she called back and said they re-reviewed my case and were going to fix it under warranty.
I spent almost 2 weeks without the laptop while fighting with Apple over a pre-existing design flaw in a laptop that had extended Apple Care.