Pricing

So today I purchased a six pack Coke Zero 300ml @ Woolies Lephalale and paid R56.49. Not long before that I was at Pick n Pay Lephalale and paid R39.99 for exactly the same product. The last time I checked the brand Coca-Cola belonged to Coca-Cola and not to Woolies. My question now is how come Woolies charge almost R16.50 more than Pick n Pay for a six pack Coke Zero? This is not fair to over charge people like that