Price inconsistency

Can you please explain to me why it would be that the items of prices between the various stores differ so drastically. I went to purchase a dishwasher today. The one I wanted to purchase at Centurion had a list price of R7499. They were however out of stock - story for another day as this is the 3rd time this store has not had stock. I was told to go to Silverlakes. So I went and when I paid I was charged R7999.00 for the exact same item? Why? Firstly I need to travel for more than an hour from where I stay to buy something and the I am overcharged? Ridiculous! Can a senior exec from Head Office call me to explain? These are not owner managed stores so why the difference? This seems to be a CPA issue and might be a worthwhile complaint to lodge with the representative body.