2002 Chevy Suburban WATER PUMP REPAIR

I TOOK MY 2002 SUBURBAN TO A CHEVY DEALERSHIP BECAUSE MY LOW COOLANT LIGHT WAS COMING ON & I COULD SMELL A SLIGHT OVERHEAT SMELL WHEN I GOT OUT OF THE TRUCK -- I HAD MY WATER PUMP REPLACED BECAUSE THIS IS WHAT THEY SAID I NEEDED. AT THAT TIME A HAD NO VISIBLE LEAKS. AFTER PICKING IT UP I COULD STILL SMELL THE OVERHEAT SMELL AND ABOUT 3 DAYS LATER THE LOW COOLANT LIGHT COMES BACK ON AND I THEN HAD A VERY PROMINANT LEAK OF COOLANT UNDER THE TRUCK. I TOOK THE TRUCK BACK TO THE DEALER AND WITHIN 10MINUTES THEY TELL ME THAT COOLANT HAS LEAKED INTO MY ENGINE. THEY MENTIONED AN O-RING AND A T(THING) THAT HAD BROKE. WERE'NT THEY RESPONSIBLE FOR MAKING SURE THESE WERE REPLACED WITH THE NEW WATER PUMP? WOULD THE 0-RING AND COOLANT OUTLET GASKET PREVENT COOLANT FROM LEAKING INTO MY ENGINE? THEY ALSO DID AN OIL CHANGE WITH THE WATER PUMP - IF IT WAS LEAKING INTO THE ENGINE BEFORE THE WATER PUMP WAS REPLACED SHOULD'NT THEY HAVE CAUGHT IT? (I HAD ALSO PAID FOR A MULITPOINT INSPECTION/DIAGNOSIS WITH THE WATER PUMP REPAIR). I BELIEVE THE MECHANIC WAS NEGLEGENT AND THE DEALERSHIP SHOULD BE RESPONSIBLE FOR MY REPAIRS? Thanx