Scope
The contact number XXX is already assigned to another contact. The contact number must be unique across all contacts.
Solution
Please check the contact in Xero, and collect the contact details-
A. The internal ID of the contact in Xero: (Open the contact in Xero, and share the ID in the URL tab as highlighted in the screenshot below)
B. The corresponding Chargebee customer ID
Send the details across to support@chargebee.com and we will perform the mapping from the backend to map the Chargebee customer to the contact in Xero.