KLM sells different types of economy ticket. To differentiate between them, one must refer to the "fare class" of your ticket. This should be fairly easily derivable from your confirmations from KLM or your travel agent.




In the example above, showing part of the e-ticket confirmation from KLM, the "class" is N for both flights.

Now see this page:

http://www.klm.com/travel/nl_en/plan...ions/index.htm





As long as your ticket has no flights in fare class "G", which can not be changed or cancelled, you will be able to make changes to your ticket. You will have to pay a "change fee", and will possibly have to pay an additional fare, based on the fares available on the date and particular flight that you now wish to travel on.

You should ring KLM, or your agent if the ticket was not booked direct with KLM, to enquire how much it would cost to change your current ticket to the flights and dates you now want. If you are changing just one flight, it is highly likely that the cost of changing the ticket will work out cheaper than just throwing away this ticket and buying a brand new one.

Just one further point, in case you are thinking of doing something like booking an alternate one-way ticket to get you to Amsterdam on the earlier date that you now wish to travel on - if you do not take the outbound flight of your KLM ticket, and then expect to be able to take the return flight, you will find that your ticket has been cancelled. This is true for almost all airlines (some Low Cost Carriers are an exception) - if you miss any flight during your booked itinerary, the ticket is immediately cancelled and you lose your remaining flights.