Never underestimate a customer's ability to be completely and utterly wrong. That's the lesson one baffled delivery person learned during one of their days on the job. Every job deals with clients or customers in some way, and at the most basic level, it's an employee's responsibility to assist them. Companies take this very seriously. For example, at call centers, most workers aren't allowed to hang up on callers, even if they're flipping out over the phone because they don't understand why th…