The Federal Trade Commission and 20 states have sued discount retailer Dollar General for allegedly charging customers more for products than advertised and failing to address the problem, the federal agency said on Monday.

“Dollar General has, for years, repeatedly mislabeled prices, overcharged consumers and failed to correct the issue despite extensive corporate knowledge of the problem,” the FTC and states said in a statement.

“The company sells thousands of household items at low prices, which are critical to its low- and fixed-income customers who rely on the accuracy of Dollar General’s pricing,” they wrote.

Representatives for Dollar General could not be immediately reached for comment on the complaint.

(Reporting by Katharine Jackson and Susan Heavey; Editing by Doina Chiacu)