I understand your frustration with the answers you have received thus far. Please understand that we can offer some guidance here on the public forums, and point you to some resources available to help you with your project, but we are not in a position to build the application for you via the forums. I suggest you start your investigation
here. If, after poking at the Call Flow Designer for a bit, you have a specific question, we can help you with that.
Building on what others have already said, I agree that the text-to-speech engines are much, much better today. I would absolutely recommend you take that approach rather than uploading a pre-recorded wav file one or more times a day. However, using a pre-recorded wav file would greatly simplify the Call Flow Designer (CFD) application to the point where a non-programmer could probably build it by referencing some of the 3CX supplied sample applications as a guide. However, I suspect for a first time CFD developer building and publishing a CFD application is going to require a considerable effort.
If you want to use the text-to-speech approach (strongly recommended) my guess is you will probably need to hire a programmer (although there are examples of how to use a web service in a CFD application too). The good news is that your project is completely feasible and there are plenty of developers with the skills needed to build the application for you (
we can help) if needed.
If you want to try and tackle this programming project yourself, I would suggest you start by downloading the CFD development tool and look at some of the sample applications. Keep in mind that to use the CFD you must have the Pro or Enterprise version of 3CX.