@Sara007 - Some of the best remedies for chest congestion and cough in infants are the simplest ones. The first thing you need to do is buy a quality humidifier to keep your baby's room nice and moist. Having enough humidity in the air will make your baby feel a lot more comfortable.
Another thing you can do is add a bit of eucalyptus oil to your humidifier so that the scent gets into the air. It is a natural solution for chest congestion.
Finally look into baby saline solutions that can help to break up mucus. A bit of physical therapy can also help your baby sleep better. There are lots of videos available showing you how to hold a baby to help with chest congestion.