I need an E-Commerce Security Specialist

General information for the business: They sell furniture online
Industry: Technology
Kind of support: Security
Description of support work: We recently built a website using wordpress. Since the website went live some users receive an error message stating that the website is unsafe, however we've done numerous security scans which come back clear. We need someone to find what the issue is and to solve it. Please note only some users experience this error so you may not see it yourself but we have screenshots to show the warning message. McAfee for example says 'This website may try to steal your information' but all reports say it's clean? We need help for an hour to try find the issue urgently
Extra notes: Proof of clean security attached taken today, we need to stop this happening as they are losing Business, and we rebuilt the site from scratch after it was hacked on an old host. It's on a new host all rebuilt from scratch and we need help. Some users don't get security issues but some (including myself on my Macbook Pro do)