Someone was trying to run credit cards through our form to hack it.

Hi, 

over the last couple days our form was being used to run different credit cards every minute. They all had the same name. none of them went through but our processing company said we should contact you and there should be a way that we can block them. 

Thanks for any info. 

thanks

Unfortunately, we cannot block someone from accessing your form.  However, you can add in unique submissions in order to limit their ability to submit the form:

http://www.jotform.com/help/64-How-to-Set-Unique-Submissions-on-a-Form

This would, however, limit other users to a single submission as well.