How many trainings would take to change the attitude of these managers?

My job is to train people.. Train them so that they can deal with the guests and make them satisfied with our products and services. I deal with not only the operational staff but also with department heads who run the show..... I have conducted several trainings explaining them that what makes a good manager but sometimes it seems like there is some built in fault in their heads that just could not be removed.

Today yet again a manager so pissed me off when he scolded a junior staff member rather bombarded him because of something that was not exactly his fault... He demotivated him to his fullest and that too in front of me just to impress me as if he is working so hard to improve the performance of his department!! I was sooo feeling like giving a punch in his face!! But I controlled the urge and did what I thought was best for the poor guy...

The incident so happend that earlier in the morning in a meeting with the General Manager this manager got a lecture about some courtesy calls that the poor guy made. (I was also there in this meeting). GM pushed the manager a little harder. Its his job to do that but this manager did not understand that we dont have to pass all the pressure to the juniors in the same way we get!! We need to balance it. So if the GM wanted him to put extra efforts and work a little harder on the courtesy calls then there was no need to scold the poor chap... He could rather had a meeting with his staff and brainstormed how to get the required results... This Manager scolded his junior infront of me just to prove that who was the real culprit!!! (I am a Training Manager so people try to portray a good image of theirselves infront of me so that I can recommend them and their performances)

As a result the guy was all in tears and was highly demotivated... I dont think that he would ever make a single courtesy call with his full heart in it!

I tried to stop this manager and tried to explain him that he was doing wrong but he didn't listen. So what did I do to correct it... I just went to the director to whom this stupid manager reports to and discussed with him the whole situation. On my way back I also met the guy who got the harsh words from his manager and tried to councel him....

I know that its a long way to go... Its not easy to change the way of thinking of people.... Being a Training Manager I just wonder that how many Trainings would take to change the attitude of such managers who break their own teams.....