The regulator has also written to 100 businesses raising concerns over how they charge additional fees and the sales tactics they use.
Online payments
The announcement is the latest step in the drive to cut back regulation and boost economic growth.
Latest Dear CEO letter addresses themes of innovation, competition and security.
The company failed to provide information on user data storage, protection and transfers outside the EU.
The payment giant is also looking to raise $2bn from investors.
Federal Cartel Office suspects breaches of German and EU competition law.