Sennheiser CX True Wireless Headphone Connection Error

I purchased the Sennheiser CX True Wireless In-Ear Bluetooth Headphones in Black from the Media Markt website on March 5, 2024, and received them on March 6th. Upon attempting to charge and use the product, I encountered difficulties connecting them. Initially, I managed to establish a connection, but only one side produced a very weak sound. Subsequently, the connection failed entirely, and I couldn't establish any Bluetooth connection. I took the headphones to the Metropol Media Markt store where they confirmed the connection issue. A service form was opened, but I encountered difficulties accessing the repair page due to a recurring "prohibited" message. Customer service was unable to resolve the issue. Although I believed the matter was resolved after my initial complaint, I revisited the Metropol store yesterday, just before the legal period was expected to expire (which, incidentally, does not align with the delivery date). Why must I endure this ordeal? I urge Türkiye Media Markt and Sennheiser to address this matter promptly and uphold their commitment to customer satisfaction.