If the spambots have cancelled your posts and you genuinely believe that what you have posted was not spam, you can politely post in news.admin.net-abuse.usenet and explain what you have posted and ask for help in preventing the spambots from canceling. Now, be advised with the exception of repeat postings of FAQs, it is highly unlikely that a post will hit a BI of 20 without being spam. You will be presumed guilty until proven innocent, so post accordingly. Remember you are asking for help. If you are posting to a moderated newsgroup and the moderator is canceling your posts, you are really out of luck.
Moderators are omnipotent in their newsgroups and can cancel anything they want.
Your only recourse here is to write the moderator and ask nicely why you are being cancelled. If you cannot come to terms with the moderator, you are going to have to find another non-moderated newsgroup. If your posts fit none of these categories, you need to track the person canceling the posts. This is not an easy thing to do unfortunately. These cmsgs are send to the pseudogroup control.