Can you get sun baked wax of without a buff?

This is the first time I've come across this so I dont know how to fix it. A potential customer of mine wants to know if I can get wax off that wasn't properly applied and its been setting on the car for 3 years. The only problem is they don't want any buffing due to their lack of trust in detailing. And I don't blame them really. Is there a way I can manage this?