As it happens I have just spent a lot of time with a scam/fraudulent operation/theft ('cos that is what it is really) on my wife's account. She hadn't looked much at her account over the last few years, overtime with Covid (she's a just retired ICU nurse) and other problems just before. She asked me to look at her recent accounts for a payment for show tickets (which hadn't been made) and I remarked "What are these payments for a card? You haven't got one, have you?" Down to the bank to ask questions, the man said "Highlight them and you have a rdv with a councillor next week". So I did, traced back four years with three colours of highlighter and finished with an awful lot of operations. I have just finished doing and checking a spreadsheet that was the suggestion of the man from our Protection Juridique, taken about a week - mainly checking. Result, three associated companies over four years have taken a total of nearly 19K€. We have absolutely no paperwork, contracts or other contact for all of this. I think we have a bit of a battle coming up, including over the fact that we have unilaterally stopped the dds without resigning the relevant contracts ('cos we haven't got any!). The group to which all this belongs are facing a class action but there may be a limit to the size of claim you can put on a class action. Affaire à suivre as we say over here.
Just a warning, avoid buying a mobile phone in a high street shop in France unless you're really sure they are absolutely trustworthy. Don't trust boutiques linked to SFR!