Exchange the shoes
换鞋

Excuse me, sir. I wonder if I could exchange the shoes for a larger one.
抱歉，先生，我是否可以换一双大号的鞋子？
No problem. May I see your receipt, please?
没问题，我能看一下您的发票吗？

Here you are.
给你。
That's right. Now try on this one. It's size 41.
没错，试一下这双吧，这是41号的。