Zoho Desk Brand- add on in Social Module

Zoho Desk Brand- add on in Social Module

Hello!

Where can I purchase brand add-ons in Zoho Desk (under Socials)? 
Zoho Desk Professional currently can have 1 Brand only. I want to add more brands so I plan to purchase add-ons but I can't seem to find anywhere in the website where I can purchase them.