Why didn't he just call the phone number on the bill? Banks buy and sell pieces of each other all the time. Calling "the bank" and hoping to find someone who knows something about your account is incredibly naive. I guess he needed that kind of naivety to create Dilbert. Maybe guys like this are able to point out the weird things we've adapted to because they aren't able to adapt themselves. Seriously, it takes a kind of mad genius to think that a randomly chosen customer service person in MegaCorpBank would have the means to access his account information or even figure out which piece of MegaCorpBank he has an account with.
All of the examples presented are cases of under-modeled, under-specified systems. If bank products were well-modeled, consistency rules were part of the system specifications, and each of the bank's products was represented with a common drill-down ("Show me when the customer agreed to these terms") API which could be wired into the CSR app, then Mr. Adams might have had one less example.
As a side note, given how much Mr. Adams can likely charge for incremental work (custom art as the given example), why does he not hire a high-end secretary to sort these things out for him?
My Mum wanted to copy music onto her multi-gigabyte Sony Walkman mp3 player. I simply showed her every single step to get the job done, and she wrote it all down, and all she has to do now is consult her notes. This is a Windows machine - I was just showing her how to rip a CD without installing iTunes (I think we used Windows Media Player).
My point is that anyone can learn a complex system if taught right. Reading the manual is no small luxury, and without the ability to learn a system, you are helpless to the bad guys who want to keep you in the dark.
