Frustrating. And scary. I have had good dealings with Remington customer service. On the other hand, I would have been happier not needing to use them to begin with. I think you are stuck in the middle of possible several unfortunate circumstances combined to make a perfect storm for you. QC issues, no stock due to wild demand, and an unfavorable political environment making things even worse. I have confidence they will fix it, but it doesn't sound like it will be soon.
Edit: They have got to be aware of barrel problems. I wonder if they could be halting things until they get a handle on it. I've had FOUR barrels and none of them shoot slugs to POA.