Struggle to sort fine with Europcar.

We have made use of a rental car from Europcar. We received notification for fine during April 2021. Payment was made immediately. Proof of payment was send to all parties. And still follow ups received from Collection department to make urgent payment to prevent further action. it seems the one department does not know the function of the other. Please resolve asap Best of it all. Various follow up reference numbers are used for follow up. This is ridiculous.