If you can go earlier ask them for an earlier date, they May not of offered it to you because a. it could be they have offered you the closest date or b.Because the earlier flights are more expensive and they want you to take the cheapest option, you could argue that's not your problem they have asked you to change your booking so they need to compromise, this often happens so if you can play them at their own game stand your ground or tell you've 'll go elsewhere.
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