Dear Sir or Madam,
I am writing to express my sincere thanks to a member of your staff, Susan Smith, for her great assistance.
I booked two air tickets for December 31. One was flight 222 to Hong Kong and the other was English Air flight 333 to Bombay. Flight 222 was delayed two hours due to bad weather conditions and I would have missed my flight to Bombay. I was extremely worried and went to a staff member (later I learned she was Ms. Smith) and told her my problem. She made a call immediately and changed me to an earlier flight.
Because of her help, I arrived in Hong Kong on time and boarded my flight. I appreciated her very much and if possible, I would like you to praise her and reward her.