Overcharged me and wont refund me

I purchased Isoboard ceilings and cornices from the Pretoria branch of Isoboard / Isofoam. The extremely rude sales lady, Alida, over charged me and I picked up the error after she had swiped my credit card but before I took delivery. She refused to reverse the transaction even though she admitted it was her mistake. She claims it would be reversed shortly by the head office in Cape Town. A week later I am still waiting for my money.<br> <br>