Spam on one of my forms

I recently returned from vacation and had an email stating that I was near my submission limit for the month.  I went through all of my forms and discovered the form named "Westbury Tell A Friend" had received 9k spam submissions that are all in Japanese.  This brought me to my 10k limit and I still have 10 days left until renewal.  I have never had a problem with this on any of my forms and I have never had to use the captcha submission field.  I have disabled the form for now.  I would like these spam submissions removed from my account and want to make sure I will not be forced to upgrade to continue receiving submissions.  This issue needs to be handled immediately.  I manage over 18 property sites and all of their contact forms are set up through Jotform.