Selecting a Japanese book ...

I have been studying Japanese for 2 years now, but, my spoken Japanese is still, not humble enough. Since I am planning to use it mostly for business conversation with customers, I wanted to polish it. With this idea I visited the Kinokuniya superstore, and somehow walked around to the Japanese section, and to my surprise there were hundreds of book on business Japanese, and I spent roughly 3 hours and could not arrive at a book that matches my level (because it is just above beginner's level) .. But after sometime I bought this book "Japanese power for living"　「生きる為の日本語力」 . I read a few pages on the way back.

The book is all about "Humble expressions in Japanese". Speaking of these humble expressions, there are two of them,
- Sonkeigo 「尊敬語」
- kenjouｇo　「謙譲語」
Sonkeigo is used to praise seniors (add extra ++)
Kenjogo is used to humble oneself (reduce your own level --)

It seems that many Japanese are starting to make mistakes here. It seems that they are starting to face the same problem as "Japanese learning foreigners", and the Japanese (elders) are trying hard to re-introduce it.

Let us take an example, If you want to inform someone over telephone to, "wait for a few minutes" The word few can be expressed as chotto→shosho→sukoshi→shibaraku (respect increases in the ascending order).