Your bulkhead is probably capped with concrete rather than being made of concrete. If the bulkhead itself is failing, there are a lot of people who can do the work, but like anything else it's a crap shoot.
Matlock Marine did some concrete work on a bulkhead for me. He did a pretty good job. Nice enough guy. Not an endoresement per se, but he can do whatever needs to be done. I highly suggest that you get multiple bids!