Are you a 4mbps user? I can't remember, :p. 4 mbps users have their own IP range, 212.xxx if I'm not mistaken, just ask to be transferred to that IP range.
I guess the best thing would be to just call them up and say, I've been undergoing slow net speeds since x, I've also noticed that I've been stuck with this IP range, could you refresh my port / help me get a new IP (emphasis on your already having restarted modem / disconnected reconnected multiple times).
If that doesn't work, ask for a tech to be sent out, you might have more luck asking him directly.