That's not quite right. I've been selling on Amazon for 6+ years and have lost selling privileges a few times (every time due to an issue with our order management software). Sometimes dealing with it was as you described. But I can state factually that they don't always indicate that you're about to be shut down, nor do they always make it remotely easy to get back on or even figure out why you were shut down.
For instance, I went through quite a Kafka-esque nightmare just a few months ago. Something got messed up with our order software so that when we shipped something it wasn't marked as shipped and the tracking info was not uploaded to Amazon for a few days during a busy season. Customers weren't complaining since they were getting their stuff. Amazon sent a warning that our late shipment rate was too high just an hour or so before they sent an notification saying we lost selling privileges. I immediately figured out what went wrong. I got the order software working right again, and I manually marked all the "unshipped"-but-actually-shipped orders as shipped and added the tracking. I wrote to Seller Performance about this, exactly as they instruct you to. I explained what happened, showed them how I fixed it, and explained how we'd ensure it didn't happen again. Their response was simply that our late shipment rate was too high and that my account was suspended as a result. I sent the same info I had sent, and this time included full tracking info for all of the affected orders (and by this time most of them had already been delivered). I received the same response as before. I tried doing their "Contact Us" methods, but no one would respond to my messages or talk to me on the phone, since the account was suspended. All anyone would say is that I need to contact Seller Performance to attempt to get back on. Finally, after several emails to Seller Performance about this, where I basically explained the situation and how I fixed it and how all the supposedly-unshipped orders were actually fine or already delivered, but just phrasing it slightly differently each time, I was unceremoniously let back on, more than a week later. I asked very politely why it took me so many attempts to get back on, even though I just told them the same thing each time, and they said they could not discuss it, and that I may have my account suspended (!) if I contacted them again about this.
So maybe you've had an experience having your account suspended on Amazon that went smoothly, but that's definitely not how it always is.
Based on your side of the story it sounds pretty shady. Total speculation: maybe someone got a ticket assigned to them and slacked off, closing it over and over with a canned response. A rep can probably watch a lot of YouTube if they do that to most of their tickets. Then when you'd reopened it by replying enough times to make them worried about their manager noticing they fixed it quietly and closed it. Asking why it took so long spooked them bad enough to threaten you for asking questions about their service/response which I imagine is prohibited unless the customer is being hostile.
Fair to guess, but I doubt that's it. The store I work for has been selling on there for almost a decade (it was selling since before I was hired), steadily, with very high customer feedback.
For instance, I went through quite a Kafka-esque nightmare just a few months ago. Something got messed up with our order software so that when we shipped something it wasn't marked as shipped and the tracking info was not uploaded to Amazon for a few days during a busy season. Customers weren't complaining since they were getting their stuff. Amazon sent a warning that our late shipment rate was too high just an hour or so before they sent an notification saying we lost selling privileges. I immediately figured out what went wrong. I got the order software working right again, and I manually marked all the "unshipped"-but-actually-shipped orders as shipped and added the tracking. I wrote to Seller Performance about this, exactly as they instruct you to. I explained what happened, showed them how I fixed it, and explained how we'd ensure it didn't happen again. Their response was simply that our late shipment rate was too high and that my account was suspended as a result. I sent the same info I had sent, and this time included full tracking info for all of the affected orders (and by this time most of them had already been delivered). I received the same response as before. I tried doing their "Contact Us" methods, but no one would respond to my messages or talk to me on the phone, since the account was suspended. All anyone would say is that I need to contact Seller Performance to attempt to get back on. Finally, after several emails to Seller Performance about this, where I basically explained the situation and how I fixed it and how all the supposedly-unshipped orders were actually fine or already delivered, but just phrasing it slightly differently each time, I was unceremoniously let back on, more than a week later. I asked very politely why it took me so many attempts to get back on, even though I just told them the same thing each time, and they said they could not discuss it, and that I may have my account suspended (!) if I contacted them again about this.
So maybe you've had an experience having your account suspended on Amazon that went smoothly, but that's definitely not how it always is.