It is weird to hear these horrid stories of Panasonic's service. Last year, when I first reported issues with the WT600 4k set, Panasonic at first was amazing, they wanted to take care of it themselves and all, but I had already made arrangements with best buy for the exchange. When I got my second set and it had the same banding issues, I contacted Panasonic and they basically just ignored me, not returning calls or emails.
As you know, I arranged a return for refund on my new AX800 and out of the blue today, I get a phone call from a Panasonic Tech asking about the banding and that they want to have me try another one. They were talking about actually driving it themselves from their San Diego, CA facility to me. They want to first look at my set and give me a new one. They also thought I was closer to them than they though and when I informed them I am about 300 miles away from San Diego, they said they would see what they can do. The tech said they want to see mine to see if the banding is similar to the ones in their labs and if my banding is worse that they want me to have one that has a lot less banding. Sounds like they are admitting the banding issues, but it also sounds like all other LCD's that the banding should not be as bad as I have on my set.
The funny part is I brought up the issues with last years set and he cut me off saying they were well aware of the "4 line" banding that every set from last years version had. I had to email them my address since they thought I was 150 miles closer, so I will let you all know what happens in the next 24-48 hours.