Rainey is right about the things she suggests to check.
It could be that they were not fed hay at their previous home and haven't got used to it yet. Once they are well settled in, you could try reducing the pellets for a couple of days and see it that results in them trying the hay.
Another dodge, though one to be used with caution, is to sprinkle the hay with a very small amount of blackstrap molasses dissolved in hot water. Just a small spoonful in a cup of hot water is about right. Let it cool and lightly sprinkle or spray on their hay. It should entice them to eat it.
Blackstrap is nutrient-rich, but you don't want to feed it regularly. Just reduce the amount over a period of days and hope they will continue to eat the hay even when it is plain.
Good luck! :good-luck: Rabbits can be incredibly stubborn.