Fast forward and my user base is now ~45k people, not massive by any stretch, but certainly not a small org, and we tend to buy Premium/Platinum support on all of our critical applications. I truly do have to "push hard" and long to get the attention of our support teams to get a seemingly simple problem supported and solved. Our support is still in the dumper. Take, for instance, a recent case with our replication/DR vendor. Our DR environment has been offline for ~3 months, does that not scream "critical?" And yet, we are still having engineers jump on a call to collect .... the same data that the last engineer jumped on a call to collect. One of our engineers, as has been not-so-subtly alluded to, resorted to a screamfest to get the attention of TAC, and not surprisingly that dressing-down got upper levels involved.
For good measure, major networking vendor possibly mentioned earlier spent 9 months, at the developer level, troubleshooting a multicast issue which ultimately turned out to be PIM not configured on all interfaces in the path. Yes, I felt like an idiot for not already checking that, but should not have the first engineer on the phone asked this?
Admittedly, we are going through a rough patch in terms of support, but it is not out of line with the past decade's experiences.