I wanted to complete Vigilante sub-mission now that I can access Rhino since it's rewarded with improved body armour hit points.
Other missions ended with level 12, announcing the upgrade received. But I'm on level 30 and the Vigilante doesn't end. The amount of money keeps increasing to ridiculous amounts, but I was after the bonus armour, not cash:
Best Answer
In GTA San Andreas the vigilante missions are infinite but after completing level 12 they stay the same difficulty and you get a body armor capacity bonus.
Unfortunately the armor bar is not updated, so if you miss the message about the armor bonus you might not notice the difference. To see if you have unlocked the bonus, all you need to do is fill up your armor bar than go to Stats / Player and scroll down to armor it should display 150.