Is there any way to request or download an updated invoice that includes company billing details from Trailhead Academy or Pearson VUE? Or should we contact the Salesforce Certification team directly for this request?

Hello @Athulya Jayakrishnan

 not that I am aware of. Does your company request you to provide such invoice ? As you are the one doing the check out, that will be your details on the invoice. However, if you company is Salesforce Partner, look with your Salesforce Partner Account Manager to buy a pack of vouchers (at a discounted price), that your top management will be able to handle/justify, and share them properly with your consultants to take their certifications, accordingly to their objectives / certification plan. This way, consultants will not be stuck with administrative tasks. 

Eric