I've had the zippers replaced as I was tired of my broken bag.
The inadequate zippers (they are good quality, but not corrosion-resistant) are one problem, but the bad bag design is another.
The bags could easily be designed in such a way that even if the zippers breaks, the bag can still contain the kite without spilling out.
My 2015 bag has an opening at the bottom of the bag, which makes no sense at all.
The 2016 bag improved slightly. I haven't checked the 2017 or 2018 bags, but I doubt they are there yet.
If anyone at NKB is reading this, give me a shout and I'll design a nice functional bag for you.