If an insurer doesn't support a particular claim attachment type, claim submission can fail.
However the claim cannot be corrected to remove the attachment, as it has Finalised status.
At present, the workaround is to cancel the claim, and resubmit without the offending attachment.
A better approach would be to provide a:
to InsuranceService which lists the supported mime types. Any attachment not matching one of these mime types would be rejected.