Do you have a smartphone? Aren't there apps that block things for you? I'll do a quick Google to check.
Edit: I just checked the app Market on my Android. There's an app called Mr. Number that lets you block calls and sms individually or by region.
http://mrnumber.com. Also available for iPhone and BB apparently. But if you don't have a smartphone, well...now's as good a time as any to get one heh.