It often makes sense to consult a lawyer. You will soon find a list of lawyers who specialise in tenancy law here. Call them and make an appointment for a consultation.
 This costs money, but you may have legal expenses insurance. If you have private legal protection insurance that includes the ‘housing’ module, the insurance will cover the costs of legal advice. If you took out the insurance before you signed the tenancy agreement, it will also cover the costs if you decide to take your case to court. It is best to clarify these questions directly with your insurance company before contacting a lawyer.
 You may also be able to apply for counselling assistance from a Berlin district court for legal advice. Counselling assistance means that the costs for counselling and legal representation outside of court are covered.

If you have a low income, you can apply for counselling assistance and legal aid from the state of Berlin. This means that the costs for counselling and legal representation outside and/or in court are covered. We have created an overview here.

 If your landlord refuses to lower your rent, you can decide to sue for your rights in court with the lawyer you have appointed.
 You bear the risk if you lose and do not have legal expenses insurance to cover the costs. Here we have created an overview of the costs that could arise.