COD BO 2 too many bugs. HAVE TO ALWAYS RESTART WHOLE MISSION.

[kaboomzxc]

Dear Treyarch, or developers of COD BO2. I have encountered bugs in BO2 too many times. a few examples is in the Fallen Angel campaign mission.
it has bugged at the stage where have to avoid been seen by mq drone. i avoided it and harper did not follow me to the drain there. and at the final stage of the mission, i switched to Brutus by accidentally pressing 5 and could not switch back to my player pressing '2'
PLEASE address this issue affecting too many people by kindly CREATING THE START FROM LAST CHECKPOINT.
I BELIEVE TOO MANY PEOPLE IS BEING ANGERED AND FRUSTRATED BY THIS AND THIS WILL CERTAINLY HELP PEOPLE IN SAVING TIME AND WILL HAVE YOU LAUDED AND APPLAUDED.
Please help us to save time and make better our playing experience by creating starting from last checkpoint.
At the part whereby recorded audio, it will be great for having a restart checkpoint , too many people have wasted their time keep replaying the whole mission.