Subscription payments are generally non-refundable once the billing period has started — a cancellation takes effect at the end of the current period and you keep access until then, rather than receiving a pro-rata refund.
Exceptions are considered case by case (for example a charge taken after you had already cancelled, a duplicate charge, or a sustained outage). To request one, email support@worldstream.tv with your account email, the transaction date and amount, and a short description.
Refunds for purchases made through the App Store or Google Play must be requested from that store. Remember that every plan includes a 7-day free trial, so you can make sure WorldStream works on your devices before you're charged.