It may not be the case in your instance, but I did have a wrench that was unable to actually turn the screw in a 3 wood when trying to adjust the surefit hosel. Essentially, the wrench was stripped, but not the screw head in the club. I happened to have another wrench that worked fine for the same club as well as others. If you have that option, may want to try (carefully) but otherwise, I would take it to a qualified fitter or location that can check.

When you say "I can no longer unscrew the surefit hosel on my driver," do you mean:
1. The wrench won't turn the screw.
2. The wrench turns the screw but it does not loosen.
3. You may have cross threaded the hosel screw on a prior adjustment making it difficult to loosen.

In case 1: On a prior adjustment: Did you tighten the screw not using the Titleist wrench? In this case you may have over-tightened the hosel screw.

In case 2: You may have to use more torque to loosen the screw with the Titleist wrench).

In case 3: I would bring it to a authorized Titleist Dealer/Pro Shop. Also, this may be the answer if everything else fails to loosen the hosel screw.

Good Luck.