Can I buy different product licences to ones we currently have within the Vodafone Business Marketplace?

Yes you can. As a Company Administrator you can buy any product available in the Marketplace for your company. 

Business Marketplace

Can I change my email address in the Vodafone Business Marketplace?
What's the Vodafone Business Marketplace?
How do I check my Vodafone Business Marketplace bill?
How do I get started on the Vodafone Business Marketplace?
How do I invite a new Company User to the Vodafone Business Marketplace?
What products and services can I buy from the Vodafone Business Marketplace?
Where can I get help understanding my Vodafone Business Marketplace bill?
What are the Vodafone Business Marketplace roles?
How do I check the status of my Vodafone Business Marketplace Apps purchase?
Who can use Vodafone Business Marketplace?
I want to buy additional licences for my Marketplace applications
How do I un-assign or re-assign licences in the Vodafone Business Marketplace?
Who’s my Vodafone Business Marketplace Company Administrator, and what can they do?
How can I buy a domain in the Vodafone Business Marketplace?
How do I assign a licence in the Vodafone Business Marketplace?
Can I get reports in the Vodafone Business Marketplace?