Hi Stuart-
Hope you are doing well.
1. Are you using the correct syntax on your XML file?
2. in the Cisco Support Field are you putting the correct file name? as shown above Example: "configurationfile=bv-jabber-test.xml"
3. What version are you using?
4. Modify the file locally, deleted from the CM or change its file name locally, then upload the new file (if you changed the name put the new one on the Cisco Support Field)
I don't know if i got what you were trying to explain so beforehand i hope this helps you.