They have added to the Accounts records an "Affiliate Partner", which is really the renamed the Vendor Name. 

I can get individual Account records by Account Name and I can get Vendor records by the Affiliate Email.  

What I can't do is get a list of Accounts buy Affiliate.   I tried vendorname, Vendor Name, Affiliate Name and vendorid.

Here is an example api call:

https://crm.zoho.com/crm/private/xml/Accounts/searchRecords&authtoken=<xxxxx>&scope=crmapi&criteria=(vendorname:<xxx xxxx>)

Thanks

Pete