a/c repair problems

CAN ANYONE TELL ME WHAT CAUSES YOUR A/C UNIT TO NOT SHUT ITSELF OFF WHEN IN THE AUTOMATIC POSITION. THE THEROMASTATE HAS BEEN CHANGED OUT AND THE MOTOR THING HAS BEEN CLEANED. AND THE COOLANT HAS BEEN PUT IN. AND A TECH HAS COME OUT AND SAID THERE IS NOTHING WRONG. DOES ANYONE ELSE A/C UNIT RUN ALL NIGHT IN THE AUTOMATIC POSITION. FOR EXAMPLE: IF I SET IT AT 68 DEGREES WHEN I WAKE UP AND CHECK THE TEMPTURE IT IS HOLDING AT 69 DEGREES AND STILL RUNNING ITS ALMOST LIKE IT CAN NOT MAKE IT TO THE 68 DEGREE MARK SO IT JUST KEEPS ON RUNNING. I HAVE TOLD THE MANAGEMENT THIS PROBLEM BUT THEY SAY ITS NOT A PROBLEM THAT THE UNIT IS NOT DOING THAT. I HAD THIS SAME PROBLEM IN JANUARY WITH THE HEAT AND THEY KEPT SAYING THAT IT WAS NOT DOING THAT BUT I KEPT COMPLAINING AFTER A MONTH OR SO OF HI ELECTRIC BILLS AND COMPLAINING THEY FINALLY FOUND THE PROBLEM. I WAS TOLD THAT A WIRE BEHIND THE THEROMASTATE WERE TOUCHING EACH OTHER. BUT THIS TIME THE APT. ARE UNDER NEW MANAGEMENT AND FOR SOME REASON I CAN NOT GET THEM TO UNDERSTAND THAT THIS UNIT IS NOT WORKING CORRECTLY. WHAT COULD CAUSE THIS PROBLEM?