Ruben Gamez, founder of BidSketch, put together an excellent step-by-step guide to doing interviews with people who have cancelled their subscription to your SaaS product. If you run a SaaS business, this is a must-read! http://www.extendslogic.com/business/jobs-to-be-done-cancel-interviews/
Doing SaaS Cancellation Interviews (the Jobs-to-be-Done Way) by Ruben Gamez