I arrived in Paris on Sunday, 28 October 2018. At the Gare de PARIS NORD station, I purchased 2 RER tickets for 5 days at a counter. The cost of one ticket is Euro 38.35 for a five day ticket. I paid by my Visa prepaid card. The lady at the counter did the following billing:
1 ticket for Euro 38.35.
For the second ticket, the lady at the counter did a wrong billing of Euro 65. So, she issued a credit for Euro 26.65.
When I saw my billing statement, there are 2 debits for Euro 38.35 and a wrong billing of Euro 65. An amount of Euro 65 is wrongly charged on my card. which needs to be refunded.
I have been going to the Nord station every day from Monday to Wednesday. The specific counter at the Nord station from where I purchased the ticket is closed during these 3 days and nobody in any other counter is able to help. They tell me to go back to the counter which issued the ticket.I do not know whom to contact to get the refund of Euro 65.
You can try to contact the RATP (Paris transport authority) directly for help using the RATP contact form.