Furniture Warehouse and False Advertising

I am very upset with Furniture warehouse and their false advertising on their website. There was a garden chair set of 8 that was advertised as a sale on their website. When I arrived at the shop, the salesman was surprised to know there was such a sale. I took it up with the store manager and he was also not aware of this sale, and that only the table of four chairs was on sale. A table???? This does not make sense at all. In fact I should properbly sue Furniture Warehouse for false advertising.