I'm looking to test new and different ideas in an existing mediation service that often takes several months of back and forth between two parties, usually over the phone and/or via mail. I want to solicit feedback from both sides quickly, while still keeping a realistic enough representation of the service. Any ideas? Thanks!
It sounds like you already have a good idea of how your users will interact with the service. The best idea is to figure out (1) what tasks you want to test; (2) create realistic scenarios that you can have users "imagine" they are in the middle of and (3) design the prototype to fit those tasks and scenarios. If you try and prototype the whole thing (or most digital services) you'll no longer be doing it rapidly!