Select such an incident from your own experience and write a claim letter asking for a refund, repair, replacement or other adjustment. You will require to include all the details of the transaction plus your contact address as well as phone number. If you can't reason of an experience make up details of an imaginary situation.
MAKE SURE YOU USE THE DIRECT APPROACH:
1ST PARAGRAPH - MAIN IDEA - WHAT IS YOUR CLAIM
MIDDLE PARAGRAPHS- DETAILS, EXPLANATIONS, REASONS
LAST PARAGRAPH - COMPLIMENTARY CLOSE