Sorry to hear about your bad warranty experience Andy. I think you have been professional in your considered post above and would have expected the retail outlet to mediate with the distributor in finding an acceptable warranty outcome.
Unlike you, I have had good warranty experiences with two other brands of gear I have purchased from "bricks and mortar" retail outlets. I too feel like a volunteer brand and shop ambassador.
Mark Shinn wrote me a personalised email through the shop I bought his equipment from and even went beyond my expectations by upgrading my purchase to the next year's model and throwing in a free board bag. I have no hesitation in recommending his Shinn brand of kiteboards and accessories.
I have also had Liquid Force gear replaced after extensive use during my warranty period. One was a bladder replacement and the other for a failed bar swivel. I was even allowed to pay to upgrade to a newer bar model (which has a more 2017 contemporary colour and a plastic covered depower line).
Interestingly I blew up a mate's Liquid Force leading edge while inflating the kite on the beach like you. The WOW surf kite is meant to take 12PSI (literally wow!!) and I used an LF SUP pump to get close to the green on the gauge. He had no issues in getting it repaired under his LF warranty free of charge after emailing pictures and a description through the shop he bought it from.
I justify buying new gear because of the warranty included in the new price. When the warranty expires, I'll either sell, donate it to a mate or use it until it dies...
Naish is now off my future purchase list. I have also heard that their lines are not as strong as LF, North, Ozone, etc... This is of concern to me as I'm clumsy, 6'5" and 100kg
Thanks for sharing your poor experience Andy and hope your next warranty goes as smoothly as mine have in the past.