I'm traveling with someone that is using a OneWorld Around the World ticket. (I'm only doing part of it without one) We had a flight from Quito to Galapagos on Sunday morning and we have a Cruise booked where we are required to have a morning flight to catch the cruise. Now the flight by LAN was rescheduled from the morning to the afternoon. They are only able to offer us a flight that is one day earlier, where we already have different plans, including a Hotel and Car Booking. So this is not suitable for us. They are unable to offer any better flights within the OneWorld network.

Now the best thing is: They won't even allow us to simple forfeit this one flight and make separate arrangements with other airlines that fly in the morning. They travel agents tells us that we A) Because they are offering an alternative we cannot cancel this flight and B) If we don't use this flight all consequent flights will be canceled.

I know that airlines are doing B) and it makes sense to me, but I simply cannot wrap my had around A).

Is this within their rights? I haven't found anything like that in the Rule book of OneWorld. Anything that can I do here?