False advertising

FRUSTRATED........... I went into the PnP express in Kiasha Park to purchase the special on the Simba Chips which was R25.50 for 2. When paying I was charged the normal price. When I questioned this the teller rudely said the special is over. So for convenience I purchased the chips at the normal price. when exiting the store I noticed the special was till the 30th Sep. I went back to the teller and questioned it was rudely told well WHAT U WANT ME TO DO. The teller just asked for my slip and gave my money back... stating HAPPY NOW. I had to now drive to another shop (Shoprite) to make the purchase. this after spending 45 minutes arguing WHY IS SOMETHING ADVERTISED WHEN STAFF KNOWS NOTHING ABOUT IT??? WHY IS THE TILL NOT SYNCED TO SPECIAL. WHY IS STAFF SO RUDE TO CUSTOMERS.I have a copy of my till slip and a pic of the special if you require it