Leasing end – costs of defective repair

Hello, My lease has expired and I delivered the car. In the TÜV report it turned out that the contract workshop has not repaired a damage properly and therefore needs to be improved. The costs for this have now been charged to me. How is the right thing to do here? Do I have to demand the money from the workshop now or do I have to clarify this between the lessor and the workshop? Thank you already in advance Jakob