Europcar doesn't respond to queries

I used a car in February 2019 and incurred a small fine during that time. I was charged an admin fee of more than 150% of the fine value for processing it. I cannot settle the fine online because it has not been transferred to my name - this is apparently what the administration fee was for. I have been told that I need to use the bank details on the back of the fine to settle it but Europcar did not send me the back page of the fine. I have been asking for this detail for over a week and get no response from Europcar, not even an acknowledgement that somebody is investigating my query. The branch does also not answer their phone, despite indicating operating hours of 01h00 to 00h00 on their website.