eDreams Charged Me Without My Knowledge or Authorization

An eDreams Prime membership fee was charged from my credit card without my knowledge and authorization. I only bought a ticket through their application and therefore entered my card details, but I did not request such a membership. I demand a refund of my money. Otherwise, I will take legal action and file a complaint with the Prosecutor's Office... There's also no one answering the membership cancellation phones. I want an urgent response.