Forums and trolls

I have discovered an example of a poorly run message forum.
Since I don't want to mention the name of the forum nor those involved, I will simply say this: The forum I went to has at least one troll on there who is a juvenile and whose posts are mostly off-topic opinions, insults toward others, or playing innocent after making inappropriate comments. This troll decided to engage in personal attacking, stalking and rude behavior after I said that they were acting like a troll. (I viewed their posts and discovered they acted this way throughout the forum.) When I then reported the troll and their many posts, the troll cried foul to the admins and may have claimed they were being victimized. The admins, instead of actually investigating the matter and discovering thru others' posts besides mine that this user was and IS indeed a troll, chose to ban me saying they didn't have time to deal with this. Needless to say the troll loved this and is still engaging in their activities.
What kind of administrator acts in this way? Choosing to push aside anyone who tries to defend themselves and report trolls or spammers? This is not the type of action I would have expected.
But I guess I have a lot to learn.
I have to wonder how many other forums or admins choose to turn a blind eye and a deaf ear to those trying to report troublemakers?