Had the same situation last month, wasted a couple of hours before finding these Milwaukee vice-grip type pliers, along with a good penetrating oil (Freeze Off or Aero Kroil). The eyelet on the ends allows you to tighten the pliers down (using a screwdriver) way more than standard vice grips:
Amazon product ASIN B00LJOR9BO
Amazon product ASIN B00LJOR9BO