Once a hex screw is stripped it can be difficult to remove. Before resorting to drilling it, try using a Torx wrench. The star pattern fits into a hex screw head and gradually tapers to the tip giving it a little extra grip to turn a stripped hex screw.
I had a stripped hex screw on a watch bracelet and a Torx wrench easily removed it. A set of wrenches costs ~$10, much cheaper than sending it for repair.