Comment by lucb1e

If the nontechnical team is refusing to forward it to whoever maintains the system, they apparently see no problem and you could disclose it to a journalist or the public. Or you could try it via the national CERT route, have them talk to this organization and tell them it's real. In some cases you could send a proof of concept exploit that you say you haven't run, but they can, to verify the bug. You can choose to retrieve only your own record, or that of someone who gave consent. You can ask the organization "since you think the vulnerability is not real, do you mind if I retrieve 1 record for the sole purpose of sending you this data and prove it is real?"

In jurisdictions like the one I'm most familiar with, it's official national policy not to prosecute when you did the minimum necessary. In a case where you're otherwise stuck, it's entirely reasonable to retrieve 1 record for the sake of a screenshot and preventing a bigger data leak. You could also consider doctoring a screenshot based on your own data. By the time they figured out the screenshot was fake, it landed on a technical person's desk who saw that the vulnerability is real

Lots of steps to go until it's necessary to dump the database as OP did, but I'll agree it can sometimes (never happened to me) be necessary to access at least one other person's data, and more frequently that it will happen by accident