Zwilling Toaster Became Stained and Rusted in a Short Time

I purchased a Zwilling toaster, and the metal part quickly developed stains and rust, turning the inside completely black. Despite regularly following the usage instructions and not cleaning it with a wet cloth, unsightly marks appeared. When I took it to Zwilling, they said they'd service it. After about 15 days, the service claimed it was normal and could happen in any machine. I'd previously used a cheaper brand's toaster, and Zwilling, despite being a well-known brand, disappointed me in terms of both quality and approach. I chose Zwilling to reduce the possibility of problems, but I'm now requesting a replacement for the product.