If someone gives you powerpoints, what are you going to do with them?
It appears that you don't know anything about Customer Service, so how are you going to teach your people?
If you intend to stand in front of a class and just read the words on someone else's powerpoint, then you are wasting your time, and that of the employees. They will learn nothing. Anyone can stand up and read a few words on a powerpoint. It is totally useless, and it is not training. They can sit at their desks and read it on their screens.
You first need to do your Training Needs Analysis, and then work out exactly what training your staff need. Then you develop a specific training course to meet those needs. What you think they need isn't what they really need.
I have said a million times here on CiteHR, that training is NOT a one size fits all proposition. Effective training needs to be tailored to the specific audience.
I have many training courses, but I do not give them to anyone else. They were specifically developed for the organisations and their needs. My training courses are useless to you.