Walmart review: Men's clothing prices

I bought 2 pairs of men's pants at Walmart. They were Ben Hogan performance slacks/pants. One pair had a manufacturer's price attached of $19.98 and the other pairs had the price tag removed. When I went through checkout I was charged $22.98 for each pair. I then returned and brought the receipt with both tags, one with the $19.98 manufacturer's tag and the other pair where the price was removed to the service desk. The lady at the desk checked the price and could not understand why the prices were different on 2 identical items, but she refunded me the $3.00 I was overcharged. I went back to where the pants were displayed and found that all the $19.98 price tags were removed. I believe it's illegal for a store to remove a manufacturer's price tag and put a higher store price on an item. I have a big problem with a multi-billion dollar company ripping off it's customers!