How do you update a CRM record from a Creator form when you don't know the CRM ID?

I have a script which simply adds a record via a form to Zoho CRM.

tenantinfo = { "Salutation" : input.Salutation, "First Name" : input.First_Name, "Last Name" : input.Last_Name, "Mobile" : input.Mobile_Number, "Email" : input.Email_Id, "Date of Birth" : input.Date_of_Birth, "Employment Status" : input.Employment_Status, "Organisation" : input.Organisation, "Monthly Income" : input.Monthly_Income, "National Insurance No." : input.National_Insurance, "Other Street" : input.Current_Address, "Other Zip" : input.PostCode, "Other Country" : input.Address_Country, "Reference Type" : input.Reference_Type, "Reference Name" : input.Reference_Name, "Reference Organisation" : input.Reference_Organisation, "Reference Phone" : input.Reference_Mobile, "Reference Email" : input.Reference_Email, "Reference Address" : input.Reference_Address, "Reference Postal Code" : input.Reference_Post_Code, "Reference Country" : input.Reference_Country, "Guarantor Name" : input.Guarantor_Name, "Guarantor Mobile" : input.Guarantor_Mobile, "Guarantor Email" : input.Guarantor_Email, "Guarantor Address" : input.Guarantor_Address, "Guarantor Postal Code" : input.Guarantor_Post_Code, "Guarantor Country" : input.Guarantor_Country };

crmResp = zoho.crm.create("Contacts", tenantinfo);

This works fine.

But if I want to update the same record I am having trouble identifying the record to get updated.

There is not "Last Record" property we can use. So I am using the input.ID property which was suggested in other forums discussions. The code I use for this is as follows:

crmResp = zoho.crm.updateRecord("Contacts", "" + input.ID + "", { "Last Name" : "New Name" });

The code runs without any error messages.

But it does not actually update any records.

It certainly doesn't update the new record created.

But it doesn't update any other records in the database.

So I am not sure where the input.ID value is coming from and where it can be found?

Thanks

Gene