I made a pick-up at the ATM, but no ticket was issued: here's what to do

Seizing the banking mediator: each bank has an independent mediator responsible for settling such disputes. You can send him a letter with your complete file.
Use a consumer association: organizations like the UFC-Que Choisir can help you enforce your rights.
Recourse to a complaint: if no amicable solution is successful, you can go to court to get your money back.
A withdrawal of unsecured money can be a distressing situation, but solutions exist. Act quickly, collect as much evidence as possible and follow the complaint procedure to put all the odds on your side. In the majority of cases, the bank makes the refund within a few days after verification.