I Could Not Return My Defective JBL Headphones at Media Markt

I wanted to return the JBL headphones I bought the next day because of a sizzling sound. They told me that a refund would not be possible and that Media Markt would send the product to the service center with a form stating that it was sizzling. I explained that I wanted to use my 14-day return right, but they refused. The product came back from the service, and they informed me that there was no problem. However, I pointed out that the Media Markt employees themselves had tested the headphones, confirmed the sizzling issue, and sent it to the service based on that. The employee there said that unfortunately, the service reported no sizzling. Despite explaining that I could not use the product because of the static sound, I was still unable to process the return. I will definitely never shop at Media Markt again. They also sell products at about 30 percent higher prices compared to online stores.