Inferior Quality Ceramic/Protective Coating

I purchased an Hisense Airfryer probably 3 years ago and the unit worked brilliantly and I promoted the product so much so that other friends and family purchased over 10 of these units. It didnt bother me until now that i noticed rust build inside throughout. My wife tells me this happened a long time ago say 2 years ago and it began to get worst. Surely the coating was meant to last longer because one doesn't really expect this to deteriorate so fast and took it for granted it has the similar coating as a Microwave oven. I'm not sure what the cause was for this to rust so fast and so bad. And is there a quick fix or do I need to invest in another brand because i simply cannot change appliances every 3 years or so because of coating issues.