Only just seen your question - I do hope the kits are still alive. If the mother still isn't feeding them, one thing that might help is this: I remember my sister adopted a baby rabbit she found, and fed him milk and water in an old-fashioned fountain pen filler. You could try any small teat-like rubber thing of this kind - but only give them a little, cow milk can't be that good for rabbits.

As for mother, if she had a little more space perhaps? Sometimes rabbits reject their babies if they feel overcrowded. But sometimes they just won't feed them.

I do hope all goes well.