What constitutes actual false advertisement?

Labor Day sale ad for a furniture store states that a specific piece is 50% off the price they have listed is $399.99 with a regular price of $799.00. There is no notation any where on the page that there are conditions to the 50% off. But when we call the store to find out if they were in stock we were told that we had to spend at least $4999.99 in order to get the sofa for 50% off. We finally found the fine print on the bottom of the back page. But it still does not any where on the ad say that the sofa is not $399.99 unless you spend the other money. It specifically states that it is 50% off. I know that I am just angry, but I am really tired of the consumers (us) getting taken advantage of! How can I get the sofa for the advertised price?