Malicious Server List

I work for an MSP, we don't use Fortinet but one of our clients do business with a client that does.  When they attempt to access their website to submit invoices, they aren't able to access this site.  I was able to track it down to the IP address of my client being blocked.  When we asked this company about this, we were told that we needed to reach out to Fortinet to get the IP removed from the Malicious Server List.  Is there anyone here that can point me in the right direction to get this taken care of?  I called support, and they told me to post here.