Glotta Support
Write to glotta.app@evolvingconstant.com. Tell us your device and iOS version, and for a problem with one episode, the show, the episode and the time in it. In the app, Settings, then Report a Problem fills these in for you.
Glotta Plus
To restore Plus on a new device: Settings in Glotta, then Restore Purchases, signed in with the same Apple Account. To cancel: iOS Settings, your name, then Subscriptions. Apple handles every payment and refund.
For podcast publishers
Write to the same address about your show.