SMEG oven and stove rusting!!!

We bought a SMEG gas top and electric oven about 3 years ago. About a year ago i noticed some rust in the oven door around the glass window. When i enquired about the rust from Hirsch i was told that we had not used the prescribed oven cleaner- hence the rust. I really am very disappointed in this SMEG stove- We paid over R16000 and to have the oven door rusting like this after about 3 to 4 years of use is totally unacceptable!!