Virgin Media has blocked my website

I am a small business owner with a Shopify store which has been operating successfully and without issue since March 2021.

Last month I established that Virgin Media had blocked my website to their customers stating that it might be fraudulent. Some people are getting a security warning to say the site is fraudulent, others are getting an alert to say that the site’s security certificate is not trusted.

I have spoken to my domain provider and Shopify and checked everything and we have no idea why the site has been flagged. I am desperately trying to get the block removed as it is crippling my small business causing distrust and frustration.

i have tried to contact Virgin Media by other ways but I have been told that as I am not a virgin media customer they will not open a case for me. 

I would appreciate any advice to get the block lifted as a matter of urgency.