SPAM attack on my forums
 

Hi Friends,
Since last two-three weeks I am getting a SPAM attack on my forums.Every second day, a username gets created using all numbers e.g.
529881277
060076438518

And then it leaves some spam messages like:
eewttrrvvddffwwqffeer

I am tired of banning them and their IPs (which show as coming from CHINA) but it seems as if some script is running that is automatically doing this..

I have email verificatin on, recaptcha on and question-answer thing on still I do not understand how come this SPAM is bypassing it all..

Can someone help please?
Thanks