If a booked flight or other confirmed service eg seat reservation carriage of pets special reservations is cancelled the passenger must inform the airline of this by telephone or in writing quoting the booking reference number before embarking on the journey

Please fix the punctuation.
If a booked flight or other confirmed service (e.g. seat reservation, carriage of pets, special reservations) is cancelled, the passenger must inform the airline of this by telephone or in writing, quoting the booking reference number, before embarking on the journey: