Well, I've worked in programming and support for two different companies, and I can tell you from personal experience that when a new employee is put on support, often it's a case of having to learn about things as they come up in support calls. It would be great if a new hire could receive months of in-depth training, plus become familiarized with all of the prior support calls, before ever being put on live support, but companies just don't have that kind of luxury. It can take years for a support rep to become so familiar with all aspects of a software system (or, in Casio's case, their many keyboard models) that he or she can solve a support issue literally with his or her eyes closed while sitting in a restaurant talking on a cell phone. And when a support rep does get to that level of expertise, often he or she either goes and gets a better-paying job with a different company, or else gets promoted to a supervisory position and doesn't actually take support calls anymore unless an ongoing issue has been "escalated" up the chain because the support rep who took the original call couldn't handle it. So, having been on the other side of the phone, I have some understanding of how hard it can be for a support rep to handle every call with ease. On the other hand, if the support rep is much good, he or she will use each call as an opportunity to learn something new-- such that it might take him or her longer to figure out how to solve your issue, but the next time the same issue comes up it can be dealt with more quickly.
As far as writing manuals, I remember hearing many years ago that a young man (in his early teens, or possibly a pre-teen) had gotten a new home computer from somebody like Tandy/Radio Shack (I forget exactly, it might have even been IBM, but you get the idea-- this was way, way back when home computers were just beginning to grow in popularity). When he tried to read the manual he felt that it was very poorly written, so he took it upon himself to write a manual of his own. Then he (or his parents) sent his manual to the computer company, and they liked it so much that they bought it from him.
I don't know if they gave him a regular job as a technical writer, but it just goes to show that sometimes an "outsider" can come up with a better manual than the "insiders" at a company.
Anyway, best of luck with the performance on Friday!