Bosch Refuses to Replace Rusted Freezer Cover on My 4-Year-Old Refrigerator

I have been a Bosch user for 16 years and this is the first time something like this has happened to me. The freezer compartment cover of my 4-year-old refrigerator is rusted. I contacted customer service and was told that the cover could only be replaced for a fee since the warranty had expired, and even if the warranty had not expired, the cover could still be replaced for a fee since corrosion would not be covered under the warranty. How can a refrigerator oxidize? This is not the first time I am using Bosch brand white goods, in short, everything electronic in my house, from the oven to the kettle, from the washing machine to the vacuum cleaner, to the freezer, is Bosch, but lo and behold, something that has never happened to me before has happened to me in this refrigerator. Whether you call it a manufacturing defect or poor-quality materials, there is a problem somewhere, the product is of poor quality, and Bosch does not stand by this product. I'm sorry, but if we buy Bosch brand white goods for ₺40.000 instead of buying them from another brand for ₺20.000 just because we trust them for their quality, you too have to stand behind your product! I want my grievance to be resolved as soon as possible.