In addition to the Desk for Interlibrary Loan Service and Charges you can also pay your fees at the pay machine on floor 7 in the Main Library.
You can pay all charges here except the ones you have received an official letter ("Leistungsbescheid") for. Remind that you need your library card for the payment.
You can also buy vouchers to buy used books (at the pay machine choose "Shop").
Cash card and cash is both possible.
The pay machine is also able to change money which might be useful if you need change for the lockers.
The pay machine cannot read some of the library cards that were issued before 2005. Please contact the Main Information Desk or the local lending desks in that cases and you will receive a new library card at no charge.