Starbucks Korea has decided to postpone its annual marketing event following backlash from staff against overwork.

The “e-frequency” reward program has taken place each winter. Customers who have collected enough stickers can redeem them for items such as diaries or free drinks.

But this year’s event was pushed back by two weeks, essentially cutting the promotion period short.

The move comes after Starbucks baristas and other employees mobilized two trucks to express their frustration with the coffee chain.

“In light of concerns brought forward, we are postponing our e-frequency winter promotion until October 28,” the company said in a statement sent to The Korea Herald.

“In advance of the promotion, we will be revisiting our operational procedures around actions to be taken e.g. partner staffing, store experience.”

Starbucks Korea also vowed to “continue to listen to its partners and customers.”

During Thursday’s protest, the trucks hired by protesters displayed signs that read, “Starbucks Partners are not expendable. Partners, who have raised their voices for the first time in 22 years, shall not be silenced.”

It was the first protest ever organized by Starbucks employees in South Korea.