有一篇关于购物的英语对话,要求篇幅中等,
III.A is returning a mobile phone he/she has bought from B.B asks an embedded question to find out what the problem is.Later,B helps A buy a new mobile phone by asking A three questions to determine A’s preferences.
这是英语口语课考试的题目，请严肃点要根据那个场景写一个对话