16) Why can't I add extra luggage when I'm checking in online?

TUI flights
This may be because you've already added the maximum luggage allowance available for each passenger. You can usually add baggage up to a maximum of 30kg per person, although this can vary by destination.
 
How to find out whether you can add more luggage
You can find out whether you can add more luggage on the Extras page, where you'll see the allowance that's currently included for each passenger on your booking. If extra luggage is available, you'll see a dropdown menu showing the extra amounts you can add. If the menu is empty though, you've already reached the maximum amount.

Flying with other airlines:

If flying with the below airlines this may be because you've already added the maximum luggage allowance available for each passenger.

Air Europa, Albastar, ASL Airlines France, ASL Airlines Ireland, Evelop Airlines, Germania, Norwegian, Travel Service and Volotea.

NEW You can now check-in online anytime, anywhere, even on your mobile. Mobile boarding passes are also available on selected routes. Go to the Flight Extras page to find out more.