Plugin Help Config / cannot be resolved or is not a field

Having an issue while trying to make the prefix of the broadcast be customizable through the config, and i keep getting errors.

Code:

public boolean onCommand(CommandSender sender, Command cmd, String label, String[] args)
  {
    Player player = (Player)sender;
    if (label.equalsIgnoreCase("alert")) {
      if (args.length == 0)
      {
        sender.sendMessage(ChatColor.RED + " You must type a message!");
      }
      else if (args.length > 0)
      {
        StringBuilder builder = new StringBuilder();
        String[] arrayOfString;
        int j = (arrayOfString = args).length;
        for (int i = 0; i < j; i++)
        {
          String s = arrayOfString[I];
         
          builder.append(s + " ");
        }
        String prefix = "&6[BROADCAST] &f" + builder.toString();
        Bukkit.broadcastMessage(ChatColor.translateAlternateColorCodes('&', this.main.getConfig().getString("prefix"));
        String value = ChatColor.translateAlternateColorCodes('&', this.main.getConfig().getString("prefix"));
        }
      }
    }
    return false;
  }
}[code]]I'm aware I have two of the same code lines as well.