Unfortunately, there really isn't much you can do to prevent them from continuing to try. I would advise you go ahead and update all your security information (all passwords, GoDaddy and otherwise) so they don't luck into the right passwords.
I am a GoDaddy End User - Just Like You * Please note that I DO NOT answer private messages. Please ask your question in the proper forum so the answer can assist EVERYONE in the community and not just you. If you contact me via PM for help, I will give you a price quote for my personal services. Thanks! *
Once your issue is resolved, please be sure to come back and click accept for the solution