Cynthia Kissner and Leonard Werner aren't lovin' it, despite the McDonald's Corp. jingle.

In fact they're so peeved at the fast-food giant, they've filed a putative class action lawsuit accusing McDonald's of antitrust violations and unjust enrichment, alleging it forces diners to pay an extra 30 to 90 cents for cheese on its Quarter Pounder and Double Quarter Pounder burgers. They are seeking more than $5 million, plus attorney fees and court costs.

“A customer who wanted the Quarter Pounder was required to order and pay for a Quarter Pounder with cheese, which was given to the customer without cheese,” according to the complaint by Miami attorney Andrew T. Lavin of the Lavin Law Group.

The couple says McDonald's could—and used to—offer diners the option of purchasing the burger without cheese, but now makes millions through all-inclusive pricing that forces patrons to buy the cheese. It notes the restaurant once offered hamburger and cheeseburger options to the Quarter Pounder—a sandwich with a 4-ounce beef patty, onions, pickles, ketchup and mustard.

“Notwithstanding the availability of the Quarter Pounder and Double Quarter Pounder, customers have been forced and continue to be overcharged for these products by being forced to pay for two slices of cheese, which they do not want, order or receive, to be able to purchase their desired product,” according to the suit.

No attorney has entered an appearance for the defense, but McDonald's corporate spokesman Khim Aday denied the allegations.

“We do not believe the claims in this lawsuit have legal merit,” Aday said in a statement. “The advertised Quarter Pounder sandwich comes with cheese. We try to accommodate our customers' requests by allowing them to customize their orders, such as a Quarter Pounder with no cheese. Additionally, McDonald's owners and operators determine menu pricing to be competitive in their market.”

But the plaintiffs, who say they dine often at McDonald's restaurants, suggest millions of other customers would disagree with Aday. They seek class certification in the case pending before U.S. District Judge William P. Dimitrouleas in Fort Lauderdale.

Their 32-page lawsuit, filed May 8, alleges three counts: unjust enrichment, violation of Florida's Deceptive and Unfair Trade Practices Act, and illegal tying arrangements under the Sherman Act. It suggests a vast class, alleging McDonald's sold millions or hundreds of thousands of cheeseburgers to diners who wanted hamburgers.

“Plaintiffs Kissner and Wernerr suffered injury as a result of their purchases, because they were overcharged and were required to pay for cheese, which is not a component of either the Quarter Pounder or Double Quarter Pounder, that they did not want and did not receive,” the complaint states.