Do they look ok? If so just get smaller crix. At their age the cup is a bad idea unless you need it to hold several days' food because you are going away from home.
Assuming they are not starving to death here is what you do: Set up a new enclosure with zero insects inside, transfer the 2 chams into the new cage, don't feed them for 12-24 hours, then pour like 5 small crix inside. The crix should be about the size of the chams eyeball lengthwise. That should break the hunger strike.