My bag being searched with no explanation after paying for my goods.

Im a loyal and regular shopper at spar Kenilworth, i run a business of food so i go there almost twice a day. Yesterday afternoon i went there with one of my helpers to buy stuff for monday, to my suprise when i finished paying a security lady with no namw tag asked to search my handbag, and i asked her why, her response was everyone with bags are searched, but another lady passed me never got to be searched. I asked her did she find what she was looking for? Dololo no response. I then took it up with a store manager who was also suprised by the whole senario. Their security supervisor then told me there are notices in the shop for searching then my question was why is it not done to everyone one and since ive been a customer there it was the 1st time in more than 15years shopping there that i would me humiliated like that. His response was call the police if you feel like we infringed your rights. Iam really humiliated and angry. Just because i had an apron, dirty boots and obviously looking tired that gave them power to think iam a *****. I spent more than R1000 in that shop everyday monthend i do my home grocery there more than R3000 religiously so. And yesterday that put doubt in my mind and id rather shop at PickN pay if this is how they will thank me for being a loyal customer.