Incorrect Price

I went to Musgrave centre pnp today and came across the safari fruit sticks on special. The price said assorted fruit sticks at R20,there was no indication that there was a price difference between the berry and fruit stick price. When I got to the till I was charged R38.99 for the berry sticks and R20 for the fruit sticks, I only realized this when I got home. This is a bit frustrating because there was absolutely no price tag for the berry sticks or indication that the special didn't include the berry sticks. The tag said ASSORTED sticks for R20. This is upsetting because it's causing me great inconvenience. There are other products on special saying which variety is excluded but this wasn't the case for these fruit sticks. Please ensure that prices are clearly indicated so that it doesn't cause us inconvenience