The error code in the SOAP fault seem to indicate a permission error. For example, a google search on error code 403 (for HTTP):
"403 Forbidden or No Permission to Access. A 403 Forbidden error means that you do not have permission to view the requested file or resource. While sometimes this is intentional, other times it is due to misconfigured permissions. The top reasons for this error are permissions or .htaccess error"
Have you confirmed that you have setup your payload correctly? Do you have to provide some authentication in the HTTP headers?