Are you talking about the "Sofortüberweisung" ?

This is a service from a business, cooperating with several banks.
You have to give away a TAN from your online banking account,
they use it to clear the transaction.

Even though they do not fraud (like using your TAN to make funny stuff),
it's an obvious risk you take.
Chargebacks are rarely happen, but they are known.
Consider it like "Paypal XS".

The fee's they require are pretty high as well.


I would describe it as
"a service which you make use of in hard times,
but if you got a little scope, you avoid it and use better alternatives".