It is a formal writing in which your objective is to express that you are unhappy with a product, service or experience that did not meet your expectations. In this text you must be polite, give details of the problem, summarize your experience and sometimes ask for compensation.
POSSIBLE TASK:
You have bought a new mobile phone and in a few days of purchase, it has stopped working. You spoke to the company representative a week ago but the customer service was unpleasant and your device has still not been repaired.
Write a letter to the company (150 words).
BEFORE YOU START WRITING...
Make a list of the problems you had. This will help you see if they make sense and organize them clearly in your text.