Schaller GrandTune Butterbean 3L/3R NI

I bought 2 sets of these tuners. I don't like the tuning stability, and one of the tuners is defective - you turn and turn and nothing happens, then there's a pinging and the string goes way out of tune. I wrote thomann and they asked me for a video to sent to their specialists, then they said they can't open the dropbox link I sent them with the video, then I uploaded it to YouTube (unlisted) and sent them the link, but they didn't care to watch it, then asked me something about the size of the tuners, to which I just looked at what the page of the product says in the specs, and referred them to it... After a few emails of back and forth they went silent and I know they don't take the issue to heart. I waited a couple of weeks then emailed them asking what they intent to do. I was told a replacement was sent, but there was no tracking number or any shipping information and I never received anything. This is the firs time Thomann have dropped the ball.