They are a new start-up company just getting going. Sh*t happens. It's too bad there aren't more perfect machinist out there like you, then there would never be mistakes.I do occasionally watch machining YouTube videos. I also work full time as a machinist, and have been since 2004. Got my Journeyman ticket and red seal back in 2010.
If they are using quick change jaws, and those jaws are VITAL to their ability to produce parts, one would think that they would have their #### together and not run out of said jaws. It would be like me running out of inserts, and having no available alternative. Completely unacceptable, and it just can't/doesn't happen. Admittedly I run lathes almost exclusively, so I'm less familiar with milling workholding methods, but the premise is the same.
They ran out and ordered more. What more do you want them to do? Probably the biggest problem is no one stocks stuff anymore. Anytime I order anything from my local suppliers, it's always a week away. I started just going direct to the factory, sometimes getting it quicker.