I purchased redmi 4a mobile through amazon. 
I found that Slim card slot holder was missing, that I noticed bit later.
I contacted people on there platforms - Amazaon, Amazon seller and Xiaomi India.
All three are passing the buck on each other and none of them are taking it seriously to resolve it.
Initially xiaomi responded that they will resolve it and asked me to visit their customer care center, I did it but they are not ready to support on it.