3819616 - Error in logs: "*** SIXT *** UNKNOWN ID-NO. / USE CD- FOR CORPORATE DISCOUNT NO"

When booking a Car, there is the following error displayed at Review and Book page:

In Concur Service Logs there is the following error returned from GDS/Vendor:

*** SIXT *** UNKNOWN ID-NO. / USE CD- FOR CORPORATE DISCOUNT NO


If your Company uses Legacy Concur Travel, the following error is displayed:



or 

There is an error during the Sixt Car booking at Review And Book page. The following error is captured in GDS logs: "*** SIXT *** UNKNOWN ID-NO. / USE CD- FOR CORPORATE DISCOUNT NO" , KBA , CON-CA-TLS-IEM-IMP , Import Credit Cards , CON-CA-USP , User Profile , CON-SRV-TRV-ADM-AMA , Test Amadeus , Problem