In light of/In view of/Considering/Seeing the fact that your expectations were not met, I'll bend the rules and give you a full refund. 

鉴于...由于...

A: Hello, I'd like to return this woolen sweater. 

你好，我想退还这件羊毛衫。

B: Do you have the receipt?

您有收据吗？

A:Yes, it's in a box.

有，在盒子里。

B: Would you like to try on a larger size?

您想试穿大一号的吗？

A: No, thanks. I just want my money back.

不了，谢谢，我只想把钱拿回来。

B: We don't provide refunds, although I'll be happy to exchange your purchase.

我们不退款，不过我很乐意更换您的商品。

A: If that's the case, can I try on a different style, please?

若是如此，请问我可以试穿不同的款式吗？

B: Items can only be exchanged for those of the same style.

只有相同款式的商品才可以更换。

A: I don't want the same style. Not only were the arms too tight, but the body was too baggy. If I get a larger size, the arms might be alright, but the body will be even looser.

我不想要相同的款式衣服，不仅袖子太窄，而且衣身太宽松。

如果我拿大一号的，袖子或许没问题，但衣身会更松垮。

B: 

In light of 

the fact that your expectations were not met, I'll bend the rules and give you a full refund. 

先生，由于您的期望落空，我这就放宽规定，给您全额退款。