Trying to kill an A Wing with a tie fighter at anything but Range 1 is not going to work in your favor usually....the A Wing is base 3 evade dice to your 2 attack dice in RB2-3
As stated before, in this scenario you should pound the bejesus out of Wedge until he goes down, let the A wing and Y Wng do their thing until Wedge is down, than go after the Y and finally the A Wing.
I state the A Wing should be last for the following reason, even if it shoots at you in RB 2-3 you will have more evade dice than are being thrown at you and even if he is in RB1 you will still be even on dice
Finally, yes sometimes it comes down to just plain luck and it can be frustratingly maddening (just find my post from last week about it), all you can do is grin and bear it, take it on the chin and go again