i am trying to s-rank "attack the refueling base", and no matter what I do, I cannot get better than A-rank. i am pretty fast and hit a payout of over 600k. i got all the fuel tanks. i got 4 helicopters. i got most of the enemies, though i left a few scrubs i didn't feel it was worth getting. i did take some damage on the final 2 guys but not an absurd amount. i've tried this like 20 times. frustrating