Preeti Gulati

I love playing this game and this is the only game I play on my play station. The only thing is that I killed helis and deathbringer that protects Haides, also, I overrode it. But after doing all this, my quest restarted.again I have to kill helis, machines on the ridge and deathbringer. Why is it happening? Is it a type of glitch or everyone else has to do it. Please help