Screwed over by car dealer and need help please?

my husband bought a car back in march and i recently was having work done on it and found out some angering news about the car. now get this my hubby bought this car for 16,800 its a used 2002 pontiac bonneville se in good condition and he got a loan out for it and we are paying it off but today while getting some work done on it i found out that the car was sold to him for triple the price it should have actually go for, mechanic told me that the car is actually only worth about 5,000. i was so pissed when i heard that we are now paying off a 16.800 loan for a car that's only 5000 and i was told the most it should have wnt for was 10,000 or 10,500 at the most. is there something we can do cause i don't appreciate nor like this at all. can we get our money back or something anything. please help he's in the military and needed the car to get back and forth to base and rushed out to buy it and the ripped him off telling him lies and glamorizing this crappy car and got him good. please help is there anything we can do i looked up the place and apparently they are known to rip off just about everybody mostly military cause its close to base and boasts greatness to lure them in.