Unfairly treated

I'm a permanent resident in South Africa with a green ID, I went to collect my parcel but they couldn't give to me because apparently they needed a South African ID so I had to go look for someone who could help me collect the parcel but the cashier started telling the lady I brought with sounding as if I wanted rob her not knowing that we knew each other, I feel like I wasn't treated fairly, I mean I was given this green ID by the South African home affairs so why should I be treated this way?