1. The Defendant’s use of the mileage 9,853 C and the amount of credit card from May 1, 2015 to October 30, 2017 to the Plaintiff.

1. Basic facts

A. On October 2012, the Plaintiff entered into a credit card subscription contract with D [Co. D], the Defendant’s telegraphic body, divided the company into E Co., Ltd. on September 1, 2014, and transferred all rights and duties relating to the credit card sector to E Co., Ltd., and thereafter E Co., Ltd. changed its trade name on December 1, 2014 to B Co., Ltd. (Defendant). hereinafter “Co. D” and “B Co., Ltd. (Defendant”) without distinguishing between B”) and the Defendant’s Internet credit card website (hereinafter “Defendant”) and issued the instant card.

The term of validity of the instant card issued by the Plaintiff is until October 30, 2017. The annual fee is KRW 100,000, and the Defendant agreed to provide additional services, including the accumulation of C mileage (it can be converted to G or H mileage) at the rate of 2,500 won per 1,500 won per use, in addition to services arising from the original function of the credit card at the time of the instant contract.

B. Around February 26, 2013, the Defendant changed the percentage of mileage accumulation through the Defendant’s Internet homepage, notice, etc., announced that the rate of mileage accumulation provided to the card members of the instant case from September 1, 2013 is reduced to 1.8 C/C per 1,500 won per use. Accordingly, the Defendant provided the Plaintiff with mileage according to the reduced rate of mileage accumulation from September 1, 2013 to April 30, 2015.

(c)Article 14 ( Points and Other Services) (3) of the relevant terms and conditions provide at the time of the use of a credit card, additional services, such as points and discount benefits, shall be maintained without reduction or abolition for at least one year after the new issuance of the credit card, and when any change in additional services is made, the change shall be made with regard to