Cancel Verv Subscription

I received an offer for "free 7 days" for the Verv app. I read and acknowledged that I had to cancel on day 7 if I no longer wanted the app. My trial ended on July 21. I did cancel, or I thought I did but today received a receipt for $41.99 for 6 months. I have filed a claim with itunes/Apple. How do I get a refund? I am wondering if I thought I had cancelled but actually did not. It is very difficult to find the cancelation on the app. They obviously do not want you to see it. Please advise. Thank you!