Write an email to the manager of a travel agency cancelling the ticket that you had bought last week.

 From       :mahira1223@gmail.com
To            :travelworld@gmail.com
Subject    :Cancellation of booked air ticket.

Dear Sir,
I have booked an air ticket of Bangladesh Biman to visit India through your agency, 'Travel World'. I am supposed to travel on 12 September 2017. But, I am afraid I will not be able to travel on that day because of some personal problems. It is really unfortunate for me that I have to cancel my booking for 12 September 2017. I am really sorry for the inconvenience. Hope to get a fresh date of travel very soon.

Waiting for your confirmation on the cancellation.

Sincerely yours
Mahira