Dentsu Inc. handled internet advertisements inappropriately and overcharged customers an estimated ¥230 million ($2.3 million) in a case that may stoke concern about the transparency of digital media transactions.

The country’s largest ad agency investigated transactions going back as far as November 2012 and uncovered 633 suspicious cases affecting 111 advertisers, including 14 examples where fees were charged when no ad placement had been made, Dentsu said in a statement Friday.

Read the full Japan Times article here.