Please find Sectigo's tutorial here:
https://support.sectigo.com/Com_KnowledgeDetailPage?Id=kA01N000000zFaP
Link to Sectigo's support form:
https://support.comodoca.com/Com_KnowledgeWeb2Casepage
Important: please select "Certificate Technical support" for reason and don't forget to add the serial number of your certificate as well as your SSL Order ID that can be found on the details page of your InterSSL certificate and in Sectigo's order confimation emails.
Important: please make sure you are entering your SSL Order ID !