Tefal Stainless Steel Knife Rusts After One Use

I purchased a Tefal stainless steel kitchen knife from a BİM store in Bornova, Izmir, last Monday. I paid approximately $8 for the product and used it only once, washing it by hand. Despite this, the knife developed rust and corrosion in less than a week.

I am concerned from both a health and product-quality perspective that a knife labeled as stainless steel and purchased from a brand like Tefal would begin rusting in such a short period of time. I was also not given any information about warranty coverage or return and exchange policies when I purchased the product.

I believe this is a manufacturing defect. I request that Tefal investigate the issue with this knife and either replace the product with a new one at no cost or refund the amount I paid.