There are a few different things that may be problems. I would start with their embouchure. Make sure they have a tight enough embouchure, because it sounds like they may be to loose. Being tighter, their pitch will raise. It may also help their tone problems. Another great things for sax players is a breathing tube. Most people are not familiar with this but it is relatively simple. Role a piece of paper into a tube the short way so that the diameter is 1.5-2 inches. Place it in your mouth and inhale with the diaphram. Be sure not to breath with your shoulders, they should not move. Doing this opens up tone but also causes great volume if you arent careful. If neither of these help solve the problem, check what reed strength they are using, if it is to strong the tone will be aweful and it may comtribute to poor picth. I hope this helps.

Tell them to push the mouthpiece further onto the neck.