After multiple bang trims gone wrong I wouldn't even bother.
My bangs were once cut so lopsided that I had to curl half of my bangs to give them volume so that they looked like they were the same length as the other side. At my next appointment the stylist mentioned that I probably didn't notice that my bangs were uneven (as she was the one who had cut them), but one half of my bangs fell before my eyebrow, and into my eye, while the other side fell above my eyebrow.
They sell bang trims in packs of two, since that's the only way anyone would return.