2002 Chevy Avalanche IGNITION KEYS

Yesterday my Chevy started this problem:
A- The key would not move out of the drum.
B- The gear would not go to park
C- When I finally managed to remove the key it did not cut the " Juice" (Battery). As a result I was left with a dead battery needing a jump.
What should I do?
My mechanica said that the best ting to do are to take the car to a Dealer and replace the whole thing: New Drum, New Keys, bla, bla, bla.
Thanks