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JEFFERSON CITY, Mo. — After a two-month investigation, Missouri Attorney General Chris Koster announced on Tuesday that he has filed a civil lawsuit against Walgreen Co. of Illinois.

Koster says Walgreens has shown a pattern of advertising lower prices on display tags, but charging higher prices when customers check out.

The Attorney General’s office said in went undercover in June and July, visiting eight random Walgreens stores in Kansas City, St. Louis, Springfield, Jefferson City and Osage Beach.

Out of 205 purchased products, 43 items, or more than 20 per cent had price discrepancies. Prices paid at the register ranged from a few cents more to as much as $15 over the advertised price.

“This level of consumer deception is inexcusable from a corporation as sophisticated as Walgreens, in fact it is appalling,” Koster said.

According to the complaint filed in Jackson County Circuit Court, Walgreens also offered a rewards membership program promising price reductions or savings at the register, but investigators said they did not always receive the savings.

Koster is seeking an injunction prohibiting Walgreens from engaging in deceptive pricing. He’s also seeking penalties and reimbursement for the cost of the investigation and prosecution.

“Walgreens is going to fix this problem in the state of Missouri,” Koster said. “They are now on our ‘to do’ list.”

If you believe you have examples of deceptive pricing at Walgreens or other stores, Koster’s office says to call the Attorney Generral’s Consumer Hotline at 1-800-392-8222 or go online to ago.mo.gov.