There are thick books about that... Extending what Tony says...
First, what you need to understand, that the customer is not the user.
Second, you don't make a data record to be filled according to a schema: you support a set of tasks divided in time and space which together fulfill the same goal.
In this current example, a wise choice would be to ask for 5-10 recordings of actual calls, and see what's actually asked, what is really important, not just what's stored at the end.
As I see, this form is popping up in several cases: both for initial contact, also for setting payment disputes, and signing off participation, all of which may or may not happen simultaneusly.
Perhaps it should have tabs for these different circumstances, or perhaps there should be separate forms for these tasks.
As the name implies, user experience is about the users, not about the customers.
Personally I usually start by asking users how their day goes and make them tell stories of specific customers ("tell me about the latest booking / payment dispute / course you have dealt with"), and show them quickly built interfaces.
There are lot of interview techniques, low-cost evaluation and research methods, find some good books on those (while I'm wary to recommend one, as it's an intranet app, About Face 3 would look like a wise choice, and either Designing for the Digital Age - so that would be from the same firm - or something more lightweight, like Killer UX or Designing the iPhone User Experience (no, that book isn't just about iPhones), or, if we want to approach this from a more technical standpoint, The Humane Interface might do)
In the age of Kindle, Kindle for iOS/ Android, Safari Books (for web & mobile) and other resources, any of these could be at your fingertip in a minute.
On the plus side: the form is neatly ordered into a proper grid!