The problem is that the wall is too solid. Vibrations on one side pass straight through to the other. You need to physically decouple your wall from theirs, which will not be cheap or easy. You could build another wall that is not attached to the present wall, but this makes no sense in an apartmet due to the excessive cost.
You need to either:
A. move, or
B. just crank it up so you can't hear them. Of course that will get you evicted, which brings us back to solution A.
You need to either:
A. move, or
B. just crank it up so you can't hear them. Of course that will get you evicted, which brings us back to solution A.