Dear________, I am写信人身份. I am writing this letter to express my dissatisfaction / complaint to you. I bought a/an________from your on-line store last month, but I found that there are some problems with it.(描述事实) Firstly,________, which is the main reason of my dissatisfaction. Secondly, ________.This is another problem. All in all, there is still much room for improvement. Before I take any further action, I do hope表达本人的愿望. / I would like to exchange it for another one or get a refund/compensation.(提出赔偿方案) Considering this situation, it would be highly appreciated if you could take my letter into seriously consideration. I am looking forward to your reply at your earliest convenience. Yours truly, Li Ming