Poor customer service

I went to the shop (Mthatha Sutherland Spar)looking for bulb then I took one from the shelves and the prices were R31.90, R29.90 & R119.90 but I choose the one for R31.90 and when the cashier was scanning it was R184.90 I was shocked! I said to the cashier let me go and check for the Spar brand surely it's gonna be lesser than this one. Then the cashier responded and say " IN FUTURE YOU MUST TEACH YOUR SELF TO READ BEFORE YOU TAKE THEN SHE LAUGHED AT ME " I was very very angry because

1. The prices/shelf packing was wrong in this case 2. I was not arguing to get that bult for that price NO! 3. She laughed at me telling me to teach myself to read as if I am that stupid person who cannot even read prices whereas the fault is theirs. 4. You can imagine that feeling when other customers are panicking on the queue and the cashier is shouting and laughing at you trying to prove that you are the one who is delaying the whole process.

Name of the cashier is Kanyisa