False advertising

Yesterday i bought pilchards that are on "special " 6 tins for 90 rands. I thought to myself that is a bargain. The cost of pilchard as displayed on shelf it's R18.99 per tin, so it made financial sense to buy the special. I was suprised when i saw my till slip showing that the actual price of the pilchard is R15.99. That showed as a minus in my slip. Shoprite you have really ******* me!