If you believe that your personal data might be incorrect, incomplete or inaccurate you can ask the company or organisation to correct your data. They must do so without undue delay (in principle within 1 month) or justify in writing why the request cannot be accepted.
A credit bureau processes information provided by your former landlord whereby it is stated that you owe him 3 months’ rent. You have just won a legal dispute and his claim for the 3 months’ rent was ruled to be unfounded. You may ask the credit bureau to correct the data it holds about you so that you aren’t put at a disadvantage in the future when credit requests are processed.