Double paid for a train

 Hello my name is Saman Zandi with card number:3258 **** **** ****, on 8th of August I travelled from Groningen to Zwolle and I had bought online ticket, But when I got there unfortunately I checked out the gate with my card instead of ticket and it took 20 euros from my account. And after that I went to the OV-chipkaart site and request for the refund for my missed check out but when I was filling the form I thought I had to write the destination which I had traveled ( from Groningen to Zwolle) and the system considered that 20 euros as a payment for the trip! so now I paid twice for the train. I attach the ticket for you.