Have not heard of Quttera but the other two I have. Usually the websites have contact details for reporting incorrect flagging, these then filter down to VirusTotal. However, even a clean listing from VirusTotal may not rectify the issue.
i also get suspicious and phishing issues when i used 4 programs and online checkers for your website. i did a further check on your firewall which shows it isn't very good and needs better protection.