thanks for sharing your question with the Wefugees community.
You haven't mentioned about your residence permit. Which type of residence permit do you have? Do you live in a camp for migrants or you have an apartment in Berlin? Do you work in Berlin? Who told you that you must apply again for an Umverteilung to Berlin? Which reason has been mentioned in the approval letter of your Umverteilung? If the reason mentioned in your approval letter is your study in another city, the Foreigners Office of the other city will ask for the enrollment letter of the University in that city anyways.
I agree with my colleague, @Meike. You should refer to the person, who assisted you in applying for an Umverteiling. I mean someone, who is in the same city and knows better about all the questions, I have posed, above, can better help you with that. Maybe he/she can help you contact the foreigners office/write to them a request to take their decision back because you did not join the university there and you do not have any apartment in the other city to live in. Maybe, if you have a rejection letter from the University or a similar letter from them, stating that you did not join the University, you should also then send this with the request to the foreigners office.
I hope my answer was useful for you and I'll be very pleased if you contact me again with further questions. I'm a member of the MBEON-staff and I‘ll be glad to guide you over a longer period of time. Mbeon is an online consultancy for migrants via the mbeon-app, which you can install on your smartphone for free. Download it via App Store or Google Play Store. You'll find me In the mbeon-app under my name „München, Herr Noori“ and get confidential one-to-one advice in a safe virtual room where nobody can wiretap messages. Further information: www.mbeon.de.