Chelyabinsk company "Corund" filed for

The Chelyabinsk company Korund filed a declaration and documents for goods imported into the customs territory of the Russian Federation to the customs clearance and customs control department of the Chelyabinsk Customs. When checking information about the goods, customs officers found errors in the customs declaration, including the wrong code for the HS. A representative of Corund, without giving an explanation, demanded that the declaration be returned for corrections. Having received a refusal, he began to argue that customs officials were required to indicate in the declaration and determine the classification code according to the HS.
Are the actions of a representative of Korund and customs officials legitimate?