A lawsuit claims that CVS Pharmacy has been overcharging insured customers for generic medications, whereas uninsured people paying cash up front aren’t shelling out as much.

The California suit, filed Thursday by seven disgruntled U.S. customers, claims that CVS has been “knowingly and intentionally” overcharging people with a “false and deceptive pricing scheme” that involves reporting inflated prices to insurance companies, according to the Associated Press.

Had customers participated in CVS’s “Health Savings Pass” discount program—which offers savings for uninsured customers—instead of attempting to purchase medications through their insurance companies, they would have paid much less, according to the suit.

The pharmacy also told insurance companies its customers were paying the higher prices, thus causing some customers to have to pay exorbitant co-payments, the suit says.

“Not only was the HSP program a means by which CVS could maintain and increase its market share by fending off discounted prices from its competitors, but importantly, CVS also intended that the HSP program would serve as a mechanism to hide CVS’s true usual and customary prices from third-party payors,” the suit reads.

Additionally, the lawsuit cites specific examples in which the pharmacy allegedly charged insured patients more, such as $135 for a 90-day supply of the osteoporosis-preventing Fosamax. Customers bearing cash up front allegedly were able to purchase the same drug for $12.

The case has been taken to federal court in San Francisco. Those who filed are looking for monetary damages and a court order that bans CVS from continuing the practice, which the suit says has been going on since 2008.

Michael DeAngelis, a CVS Health spokesman, said the pharmacy has yet to be presented with the suit, and wouldn’t comment on the matter. He cited a similar Massachusetts lawsuit that had been dismissed, telling The Wall Street Journal that “co-pays for prescription medications are determined by a patient’s prescription coverage plan.”