A. The Plaintiff is an association established to implement a new apartment construction project of a regional housing association in Gwangjin-gu Seoul Special Metropolitan City (hereinafter “instant project”), Defendant B is the president of the E architect office, and Defendant C is the architect of the E architect office.

B. On June 5, 2015, the Plaintiff entered into a design service contract (hereinafter “second service contract”) with Defendant B, with the same content as “PM service contract” as “the attached Form,” and between Defendant C and the same content as “the standard design contract for a building” (hereinafter “second service contract”).

C. On June 17, 2015, the Plaintiff paid Defendant C KRW 96,070,000 as the down payment for the second service contract on June 17, 2015 in the name of F, and KRW 80,000,000 as the partial payment for the service contract on August 13, 2015 in the name of G Co., Ltd., and KRW 20,000,000 as the payment for the service contract on August 13, 2015 in the name of G Co., Ltd.

On October 30, 2015, the Plaintiff sent a content-certified mail requesting the return of the down payment, etc. already paid, when Defendant B did not perform one service by November 10, 2015 to the Defendants by November 10, 2015. At that time, the content-certified mail sent to the Defendants.

E. (1) On the other hand, the Plaintiff et al. concluded a design service contract with H Construction Office (hereinafter “former Construction Office”) with respect to the instant project with a total floor area of 45,527.25 square meters, and revised the contents of the contract on two occasions. The final modified contract was the total service cost of KRW 1,631,50,000 with the same total floor area around June 2015, and the previous construction office discontinued the design service work after concluding the first service contract.

(2) After entering into two services contracts, the Plaintiff provided the outcomes of design drawings and specifications, etc. (hereinafter “previous outcomes”) received from the previous construction office to Defendant C, and the Defendant C used them to provide the design drawings on June 2.