I hate to say it, but it seems the reason they haven't done anything is they can't do anything. That sort of bug is probably not fixable without rerolling your character data back to an earlier time, and no doubt SE are aware of just how long it's been since you first identified it, meaning if they were to resort to this rollback, it would fix the issue but you would loose everything you've done since that point in time (other quest completion, items, levels/exp etc), something I'm sure you would not be very happy about to have happen. I really think there's no easy solution to this sadly.