It's still too small. Getting different birds would not solve anything. I would trash the coop all together.wait I have a solution! I'll just trade my birds in for banthams or a mini breed!! instant room savings
At the very minimum, they need 5sqft per bird in the coop, and 10sqft per bird in the run. Not a shoe box sized coop.
I would immediately start work on improving their setup. There are lots of chicken coop plans here. And the members here will be more than happy to give you advice on how to build something better.
For now, are they free ranging during the day?