CS2D also supports wildcard IP bans. If this guy has an IP address that constantly changes only slightly, you can ban all IP addresses in a certain range.
Suppose he uses IP address 11.22.33.1. You ban him, the next day he returns with IP adress 11.22.33.2, which isn't banned. You ban him again, the day after he uses address 11.22.33.3.
You could then ban the entire 11.22.33.xxx group by banning the IP address 11.22.33.*
This is, however, not without the risk of banning innocent people using the same ISP.