If you can't do tank upgrade or return the fish, especially if its a lfs
and not a chain pet store. My lfs
here does not accept returns for fishes, only trade ins which works like trading in a car. I suggest doing what you can with what you have to work with right now. Heres a few suggestions:
First, rearrange the decors, rocks, plants, etc. Take out the dominant lab put it in a different tank/container, and put him/her to the tank after a few minutes. That should lessen his/her aggression. Also, it would give them time to establish territories all at the same time. This technique worked for me with my dominant front.
Second, as overstocked as your tank is already, I suggest putting another lab in there with the other two replacing one of the CA
cichlid. Texas, preferably. Two mbuna cichlids of the same species together often cause a lot of problem since both will fight for dominance of the tank. Three labs should spread out the aggression a bit.
The people here already identified whats wrong with your stocking, so I am not going to mention them again. You would probably have to choose whether you want to keep the african cichlids or the ca
cichlids. I have seen people have 4 sub adult yellow labs in a 29g before so it should work for a while, an upgrade should be kept in mind in the future. They look awesome full grown especially the male. I have only kept african cichlids except for flowerhorn so I would suggest going with african cichlids and keeping the labs and peacocks. Anyways Good luck!