I would like to add our VAT number to our account how can I do this please?

Hi,

Are you referring to the subscription invoice? 

Here's the invoice of the last payment you made: https://sites.fastspring.com/interlogy/order/invoice/INT200504-8506-76245B?_ga=2.144873200.593939993.1587930921-695392028.1587930921

Do you want to add VAT on it? Please provide more information or details about the issue so we can assist you properly.