A: Can I help you, madam?

B: Yes, I bought this sweater yesterday.

A: Yes, I remember. Is there a problem?

B: Yes, I'm afraid it's too small.

A: What size is it?

B: It's a small. Do you have a medium?

A: I'll go and check. Just a minute.

I'm sorry but we don't have this sweater in your size. But we do have this one and it's the same price. Or you can have a refund.

B: Erm...I'll take this one then, please. Can I try it on?

A: Yes, of course. The changing rooms are over there. Is everything OK?

B: Yes, this one fits perfectly.

A: Good. Do you have the receipt for the other sweater?

B: Yes, here you are.

A: Brilliant.