我要退貨,怎么說?

我要退貨。 I'd like to return this. / I'd like to get a refundonthis.
    我想要換這個(gè)東西。 I'd like to exchange this.
    A: Excuse me.I'd like to exchange this blouse. 對不起,我要換這件襯衫。
    B: Whats the reason？ 什么原因？
    A: Its the wrong size.尺寸不對。
    B: Do you have the receipt？ 你有收據(jù)嗎？
    A: Yes,I have.是的,我有。
    B: Go ahead and pick up the center size and bring it here,please. 請去挑尺寸合適的來。
    A: Ok, where is the fittingroom？ 好的,試衣間在哪？
    B: It's behind you. 就在你后面。