Is my Son responsible for this bill?

Upon graduating from a technical school and receiving his associates degree in Computer networking,, my son transfered to another University to pursue his education , After 3 weeks of class attendance and to be more exact only 64 hours of class time, he received a term bill for $8,000, He utilized all of his financial aid while at the technical school, since no aid was available he was told to "Deregister""
the school insist that he is responsible for the whole term bill of $8,000 I highly protest there policy and think this is absurd, what are his rights? - Is this your question? Add additional information