Unable to Return or Replace My Faulty Xiaomi Robot Vacuum

I bought a Xiaomi robot vacuum from Media Markt on November 8, 2022. It broke down about a month ago, and we took it to the same store for repairs. After a month, I received a message that said, 'Your item is ready; you can pick it up from the store.' When we went to pick up the item today and presented the documents, we were told that the item could not be repaired and that a refund process had been initiated. Despite my objections and the fact that I had not been informed, I signed the paper. They stated that a refund operation for the amount I paid on November 8, 2022 had been initiated. I need your help because I cannot agree with this. If repair is not possible due to a breakdown during the warranty period, I request a new one. I am currently unable to purchase the same product using the refunded amount, and I am losing money. My problems must be resolved. Please do something.