1234, Main Street
Boston, MA 02123
<Recipient Address Goes Here>
I wrote you a letter [date], and I expressed my dissatisfaction for the service I got from your company on [date].
In my letter, I requested an explanation for the possible solutions for this problem. But, since then I am yet to receive any reply from you.
I have been trying to contact you since the last few days. I want to say that I want to keep the relation with you, but I am really very unhappy the way [Employee name] treated me.
Please reply immediately so that we can solve this matter and continue our business.
I look forward to hear from you.
encl: <List of enclosed items goes here>