Import Calls - Zoho CRM - Does not import Account and Contact information

Import Calls - Zoho CRM - Does not import Account and Contact information

Can anyone help?

I want to use Zoho for my business and have migrated some sample Accounts and sample Contacts related to those Accounts using the import tools, without any problems.
I have then tried to migrate the Calls related to those Accounts and Contacts and keep hitting a problem:
I am able to import the Calls but the related Account and Contact information does not import so I am left with Calls that are not related. The Account (Related To) and Contact fields remain blank!
To check that I had the format of my CSV import files right I created some test calls in Zoho and exported them. I then tried to re-import the Calls, from the CSV data files exported from Zoho, but again the Account and Contact information was not imported with the Call information.
I raised a ticket with Zoho, explaining my problem, but the response was to give me the instructions that I had already tried.
I guess with 8 million users there must be someone else with this problem. I wonder have they solved it, or did they just abandoned Zoho for an altenative system the actually works?