By Jessie Yeung, Yoonjung Seo, CNN(CNN) — The headquarters of Starbucks Korea was raided by South Korean police on Wednesday, as they continue to investigate the coffee chain that faced a nationwide backlash and publicity crisis over a disastrous ad campaign. It’s the latest headache for Starbucks in South Korea after an ill-timed ad campaign several months ago sparked public anger, forcing it to apologize and fire an executive. The Starbucks campaign in May provoked criticism from South Korean President Lee Jae Myung, who was elected after Yoon’s impeachment and said he was “enraged” by the campaign, Reuters reported. Starbucks Korea issued a formal apology that day, shortly followed by Starbucks Global, which said an investigation had begun into what went wrong. The day after the campaign launch, Shinsegae Group fired the CEO of Starbucks Korea, citing “inappropriate marketing.”