Ozon, which pioneered the Russian e-commerce sector in 1998 and is often referred to as Russia’s Amazon, holds around 10% of the country’s e-commerce market. The company has recently started to ramp up its efforts to grow its business, raising a $155 million loan to build up its logistics and warehousing system and eyeing an IPO in two years.

Couriers at one of Russia’s biggest online retailers Ozon staged a strike in St. Petersburg against low wages on Saturday and Sunday, disrupting deliveries in the country’s second-biggest city, the Fontanka news website reported .

Ozon’s couriers say that they have been underpaid for three months after the online retailer overhauled its payment system over the summer.

Around 200 Ozon couriers joined the strike, Fontanka reported Sunday, adding that the workers have also formed a trade union to try to fulfill their list of demands.

The outlet reported that Ozon customers had their deliveries suspended for two days.

The work stoppage affected “only St. Petersburg; deliveries are working as normal in other cities,” an Ozon spokesperson told the state-run TASS news agency.

The couriers agreed to return to work on Monday after Ozon’s management vowed to meet some of their demands, a St. Petersburg-based labor union representative told the MBKh Media news outlet. But they said they will strike again if money doesn’t appear in their accounts by Monday evening.