用英语写一份投诉信，该怎么写

Dear_____,
①I am ______（自我介绍）. ②I feel bad to trouble you but I am afraid that I have to make a complaint about.
③The reason for my dissatisfaction is _____（总体介绍）. ④In the first place,______（抱怨的第一个方面）. ⑤In addition, ______ （抱怨的第二个方面）. ⑥Under these circumstances, I find it_____（感7a64e58685e5aeb9336觉） to _____（抱怨的方面给你带来的后果）.
⑦I appreciate it very much if you could _____（提出建议和请求）, preferably ______（进一步的要求）, and I would like to have this matter settled by _____（设定解决事情最后期限）. ⑧Thank you for your consideration and I will be looking forward to your reply.

To whom it may concern,
I'm writing to complain about the SQ200 I bought from your department store the other day. It worked very well the first months,however, when I used it later, I could neither send my friends messages nor take photos with my cellphone.

I think you will try to help me solve this problem.I have two options here, maybe you can take it as reference. First, I think I can change my phone to another one if possible.Second, maybe you should pay me refund because of the issue.

I hope you can figure out which measure to take wholeheartedly.Your cooperation will be highly appreciated.I'm looking forward to its solution.
Towhomitmayconcern, I'mwritingtocomplainabouttheSQ200Iboughtfromyourdepartmentstoretheotherday.Itworkedverywellthefirstmonths,however,whenIuseditlater,Icouldneithersendmyfriendsmessagesnortakephotoswithmycellphone. Ithinkyouwilltrytohelpmesolvethisproblem.Ihavetwooptionshere,maybeyoucantakeitasreference.First,IthinkIcanchangemyphonetoanotheroneifpossible.Second,maybeyoushouldpaymerefundbecauseoftheissue. Ihopeyoucanfigureoutwhichmeasuretotakewholeheartedly.Yourcooperationwillbehighlyappreciated.I'mlookingforwardtoitssolution.

(右上角)Dec 日期
(左上角)Dear Mr.Manager:
（起一段,空两格）,I’m writing to complain about the poor quality of mobil phone in your store.I bought an SQ200 mobile phone at The First department store.The mobile phone couldn't sent message and take photos after a short time.I hope The First department store can exchange a new one with me or return me the whole money.（起一段,中偏右）Yours,（起一段,对齐上排）作者名字、

一个例子供参考：
Dear General Manager Mr.XXX
With all due respect, I am writing to you a serious letter to get either refunded or exchanged on a washing machine purchased at your department store on 17th, May.
Only two week from the date we made the purchase, the machine was no longer functional and remained broken after being repaired again and again. I suspect the authority of the salesperson to make the decision, and therefore I am turning to you for your kindly help.
Sincerely
XXXXXX

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