Post 1: Investigate other types of customers you may have to deal with and how to treat them.

Your document was really good since you covered almost all types of customers, most of the times you get people who doesnt know how the system/service works, if you are polite, fast and accurate you wont have any problems.

Because customers usually look for people that cre about them and to get things done within a rational timeframe, also they dont want to keep calling for the same thing over and over again.