Liven Charged Me 49.99 € Without Notice and Ignored My Refund Request

Downloading the Liven app seems like a fun approach to find eateries and collect prizes. About a month later, I discovered that my account had a 49.99 € renewal charge—something I knew absolutely nothing about. Not one email or notice stating my subscription will be renewed. I also looked at my Apple ID subscriptions to see if Liven was listed before this, but it wasn't, therefore I figured it was a one-time purchase. I cancelled the subscription right away and called their customer service for a refund as soon as I noticed the payment. After ten days already, I still haven't heard anything. From a provider I trusted, this seems quite devious and improper.