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.