参考范文：

Dear Sir，

　　 I am writing to you for the mobile phone of Dephone-S250 I bought on 20th Apr.2008 at Tele Mall in Wuhan, P.R. China. Ten days after that, it didn’t ring and send short messages. Then I took it to the seller, but was told that the model had been sold out and I had to wait at least three months for a new one. Later I went to the repairman. He said since it was a new model in China, it was impossible to fix it without the right spare parts. I was so desperate on hearing that. How can I wait that long? Therefore, I require that you send me a new one of the same model within a month.

　　 Thank you for your consideration.

　　 Sincerely yours,

　　 Bu Manyi