Price Theft

On Saturday 7 August I purchased two Black Trough switches from Builders warehouse Kempton park. The shelf marked price was R8.40 , when I check the slip I was charged R20 for each. I went back and took a picture of the shelf price. This is unfortunately not the first time that this has happened at builders, it happened with an Aloe plant I purchased around three months back. The issue here is that the South African law is very clear on the pricing of goods in stores and the shelf price is the price the consumer pays. Unfortunately lately many stores are taking advantage of the fact that many consumers will not argue or bother returning if they realize that the price is different and in many cases deliberately do this with small items as they know that customers dont notice or as mentioned won't come back. The problem is that it is theft as they telling you that the item you purchasing is R8.40 ,but when you pay take R20 from you, essentially *****ing R11.40 from you. People will say that well its only R11.40, the question is if I had put an item costing R11.40 and walked out the store would Builders say it's ok its only R11.40. They would have charged me with shoplifting. It is really annoying and would rather use another shop in future. Fact is that Builders warehouse in Kempton Park stole R22.80 from me today and because I'm a simple little person it's ok. Problem is how many simple little people are being ****** from.