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!
Mock role-play with both parties at the same time (remote or in the same building). Schedule an hour session, pay for their time. This is the fastest method.
In your question, you mention "often takes several months". I would assume there is a scenario that doesn't take several months. I would focus on testing only those shorter scenarios if possible to reduce the timeframe from other types of lengthy encounters with your service.