【答案解析】Dear Manager,
I make bold to write to complain about the quality of the cellphone I bought yesterday at your department store.
Problems of the cellphone have emerged one after another during the day in my possession. Firstly, the screen frequently turns black. Secondly, the battery can"t be fully charged, and it can only maintain the cellphone"s operation for two hours.
Therefore, I am writing to you in order to sort out the problem. I wish to exchange it for another cellphone or declare a refund.
I look forward to receiving extreme attention for my problem.