Poor quality microwave

In October 2018 I bought a Defy Microwave / Grill combo at Makro. 34 liter. Within months it started giving off a chemical smell when in use. I contacted Makro and they informed me that it has to go in for assessment. Which I understand from a retailer point of view. Upon closer inspection, I saw that inside, on the stainless steel, there are rust marks. I have never heard of stainless steel rusting. It only shows poor quality and could explain the smell. It was handed in at Makro. I spoke to Sharon. I am really not interested in keeping such quality.