ACDC overcharges in store

Saw a product online for R310 (Inc.), when I went to the Silverlakes store to buy the product, they tried to charge me R 538 (Inc.). After I pointed out that the website shows a much lesser price the sales lady merely said that the online prices are different from the store prices and they won't sell it for the online price.

I tried to create an account online, so as to order the product online, my online account still hasn't been activated, after I clicked the confirmation email link.

I informed them via email that the account activation doesn't respond, it has been a week since I've sent the email to them, they haven't responded.