Consistency (in customer service)

Inconsistency in customer services can cause confusion. Recently I encounter a problem because the mobile service company I used asked me for a "Customer No." for a certain kind of service. I look through all the relative documents but couldn't find such a term. Then finally, I called the their hotline (while is not quite hot) and learned that it's actually the "Account No." that is printed on the bills. My goodness, why didn't they use the same term so that I could have save the time for searching?

That's one simple thing for any company to do, but a great help for people, who are the greatest assets of the company.