painting the property

Maintenance

I have two tenants in a property since April 2009 and they have just signed another contract for another year at a very reasonable rent for the area. Before they signed the contract they had a list of things they wanted done and I did them and they said that they were very happy.
Then I had an e mail from the guy saying that his girfriend is expecting a baby (already 4 monts pregnant and had not mentioned it)
They then asked me to paint the hallway, bathroom, and 2nd bedroom for the baby. I agreed and because i like to keep properties in good order I put a new carpet in the bedroom and painted part of the front of the house. They are now complaining about the builder not turning up on saturday and they want more painting done to the inside of the house.
I am getting very fed up with their demands and I would like to know if I am justified in telling them that the painting of the inside of the property is their responsibility.