Earlier quoted context omitted.
I missed something: why do you as a seller have to enter your bankdetails?
That is the thing - you don't. In Czechia, something called bank ID is commonly used to authenticate. The point is to verify it is you, for example when you sign a contract online, fill in tax returns online... stuff like that. The way it works is that you are on some site, you get redirected to your internet banking, you log in (that's what I meant by "bank details", I am sorry about expressing myself so clumsily),…
I dont have many banking relationships, using 2 banks and there is not even a password to remember, all login is done via authentication apps.