>>791
最近英語使ってないので自信ない。得意な人が見たら直してくれると思うけど

I'm sorry for bothering you.
I found a defect in CD set titled (CDセットのタイトル名） which I bought from you.
12th CD in the set is unplayable at 3:30 of Track No. 10 due to, I think, failure at pressing it.
Could I ask you to change it for non-defective one? If yes, should I do?

2行目は原文にないけど必要なら。
最後はちょっと下手すぎかもね。