Years ago, I worked in a payroll department. NOBODY calls payroll because they're happy. Sometime after that I was the point person for a small call center, and I thought people calling about furniture would be less upset than people calling about paychecks.
I suspect where people can MOST get upset lies somewhere in between the urgent - where most energy is going to resolve the issue - and the personally unimportant. Like sofas. Getting mustard. And what kicked this off, WH40K.