Challenging your prospects is a highly effective approach when you’re trying to convince them to do something different than what they’re doing today. But what about when it’s time to retain your customers and get them to pay more? Not so much. For the “Why Stay” and “Why Pay” conversations, challenging your customers will actually set you back.

This study, conducted with a professor from the U.K.’s Warwick Business School, confirms the most effective messaging framework for handling a delicate but essential question: How do you convince your customers to stick with you and pay more without tarnishing the relationship?