1. All appeals filed by the plaintiffs are dismissed.

2. The costs of appeal are assessed against the Plaintiffs.

The purport of the claim and appeal is the purport of the appeal.

1. Judgment on the plaintiffs' assertion

A. The gist of the Plaintiffs’ assertion 1) is the husband and wife, and while using the Defendant’s mobile phone service from February 2010, the Plaintiffs are each contracts to change their mobile phone devices with the Defendant around November 7, 2013 in order to change their respective mobile phone devices (hereinafter “each contract of this case”).

(2) After the conclusion of each contract of this case, the plaintiffs were found to have been unable to use the mobile phone service of other mobile operators, and the defendant demanded the plaintiffs to pay the balance of the installment payment for the mobile phone under each contract of this case, and at the time the defendant already received KRW 254,850 from the plaintiff A and KRW 235,150 from the plaintiff B as the installment payment for the mobile phone which the plaintiffs knew of each contract of this case. However, each contract of this case is null and void or revoked for the following reasons. Thus, the defendant is obligated to pay the plaintiffs the total amount of the installment payment for the mobile phone which was already paid to the plaintiffs (=254,850 won) due to the return of unjust enrichment due to the invalidity of each contract of this case.

① At the time of entering into each of the instant contracts, the Plaintiffs did not read the terms and conditions of the contract, and sought an explanation from C, an employee of the Defendant’s agency, to the effect that “No installment payment exists for a mobile phone, and there is no need for the Plaintiffs to pay the installment.” As such, the Plaintiffs concluded each of the instant contracts, and there was no declaration of intent to purchase each of the instant mobile phones through each of the instant contracts.

② The Plaintiffs did not know the terms and conditions of each of the instant contracts and did not know it properly, and C concluded each of the instant contracts with the Plaintiffs with the knowledge of the aforementioned circumstances. As such, each of the instant contracts is governed by Article 104 of the Civil Act.