Switching Between Subscriptions
When you upgrade to or from the Pro Plus to the Star subscription level, Apple should credit your account for any difference in remaining credit for the different subscription within a few days as part of the same subscription family.
Apple * iTunes
iTunes handles all returns/refunds of apps. If you need to cancel a subscription, see here on how to cancel a subscription on your phone:
For other purchases, to request a refund, please open your iTunes Store, click on your username in the left corner and enter your iTunes password.
Click “see all” next to purchase history, find Fitdigits, and click the arrow next to the app. Next click “Report a Problem” link under the “Report a Problem Header” and a new page should come up to report a problem. You will then be prompted to enter the reason for your refund. From there, it will be up to iTunes to honor the request.
Again, sorry to see you cancel! If there is anything we can do let us know!
Android * Google Play
To get a refund from Google Play, see here for more: