Tempering with goods

On the 25th of October my aunt went to send me a brand new iPhone 13 via Postnet Malvern Durban branch, parcel no PPA*** when I went to pick up the parcel, I found a 1kg bag of something that looks like instant porridge, I opened the parcel in front of the cashiers because the weight of it made her suspicious. We immediately reported the matter to Postnet but they've beeen saying they are doing an investigation.