Makro sells defective goods

Makro sells defective products and the staff there refuse to accept that they are selling defective product and tells my wife that we are using the product wrong.

The product is a bicycle which I've been trying to teach my son to ride and he kept complaining that it's hard to turn, when I looked at the pedals, I saw that one of the pedals are broken and hence doesn't turn and now Makro Strubens Valley doesn't want to exchange it and insists that it's not supposed to turn and made my wife look stupid when she explains this to the staff at the store.