Well you will definitely need to find a cage that is completely safe for them or they'll just keep escaping. :/ Even if you just buy a cheap hamster cage right now, then look into getting a more suitable cage. Is the big cage safe for them?
You have to remember that they will be really scared, they are just babies and they don't know you or the house yet. You will need to give them time to come out. If they are definitely still in the wall, could you put some nice food at the very front of the hole and some more just out of the hole to try encourage them out? I don't really know what else to suggest, I really hope you get them back.