false representation on company website

so, if you go on to the Dominos website, you will find that it depicts their pizza sizes with sketches that clearly show the following: small=4 slices, medium=6 slices, large=8slices, x-large=10. which would make sense if that was what you would be getting. we ordered an x-large pizza for delivery at work only to find out that it contain 8 slices, same number of slices that you would receive if you purchased the large size. but we paid for X=LARGE. upon contacting the store were advised, in a extremely rude way, that the website is incorrect and the woman hung up when I asked for her name. so why is Dominos conducting itself in this manner, well, it would appear that this is meant to induce a customer to buy pizzas relying on false misrepresentation of the actual fact, therefore, Dominos' is in contravention of our rights as Consumer's in terms Consumer Protection Act 2008, more in particular, the \Right to fair and honest dealing - false