According to the agreement concluded between JSC "Stroy

Under the contract concluded between JSC Stroyservice and the individual entrepreneur Fedorov, she undertook to transfer the cargo to the latter. Volvo cars in exchange for a 3-room apartment owned by Fedorov. However, instead of a Swedish truck, Fedorov was offered a Kamaz-supported car with a trailer. Considering that the price of "Kamaz" is much higher than the apartment, Fedorov agreed to accept it, provided that the society would pay him 100 thousand rubles. Accordingly, the agreement was formalized in addition to the original contract. Subsequently, Stroyservice JSC refused to pay 100 thousand rubles and demanded that Fedorov return Kamaz, referring to the fact that the supply contract concluded by the parties did not provide for a substantial condition on the deadline and, therefore, could not be considered concluded. Fedorov objected that the parties initially concluded an exchange agreement, for which time is not an essential condition, and the extra payment itself does not turn an exchange agreement into a sale or delivery. The dispute was submitted to arbitration.
Question: solve the problem?