After booking the trial subscription, the normal price was charged by mistake.

If you purchased the trial subscription via one of the stores (Google Play Store or Apple App Store), all your data is being stored at the time of purchase and the trial subscription is valid for the first 7 days. If you cancel within the trial period, access to all content ends after 7 days. If this is not the case, the trial subscription turns into a regular subscription. 

If you cancelled within the trial period, it is possible that the cancellation overlapped with the payment collection. In this case, you should talk to the store where you purchased the subscription. 

The subscriptions are acquired via and managed by the stores. Since Google and Apple are independent companies, we have no insight or access to this information or data and can unfortunately not help you here. Please contact the store and explain the situation. They will certainly help you quickly. We know from other customers, where cancellation and payment overlapped, that a refund was made.