Idk if it’s a French thing, but you can be pretty sure that no customer-facing employee is going to engage its employer by writing anything.

They are probably not allowed to do this and if they do it anyway, it’ll probably cost them their job (or any hypothetical promotion).

It’s a cultural thing here that customers never really meet employees with powers to bypass the established process. It’s not limited to airlines but it’s pretty much the case of any company : the employee you talk to never have any latitude and you always have to escalate if you want to hope anything.

There is a reason we are known to be yelling all the time : it’s often the single and best way to escalate to a more powerful employee.

(btw, the employee isn’t at fault so the best thing to do is to be polite without yelling but insisting until you are bothering them to much in their job that they have to call their manager)