Call Mr. or Mrs. Okoreogo. Phone Number 00494521788318. Tell her/him the 'Aktenzeichen' 613284339 and inform her/him, that you have payed the ticket yet.

If she/he asks for it, send her the receipt. That´s all.

What you are experiencing is everyday life in germany. We call it here 'Verwaltungswasserkopf' ('public administration hydrozephalus' ).
The one hand does not know what the other does.

LOL! Little joke in pretty bad english for our german members.