Doing this may not help because normally customer does not have fax machine.
To archive this we must
1. Record and Deploy new voice file
2. Clear voice cache
3. Modify ICM script to transfer to RightFax instead of Premium Cert skill group
But I suggest to
Disable menu 00 by deploy silence voice file to disable this menu and wait until RightFax final flow is success. Doing this may not help because customer may press 0 to contact CSR to get premium cert.
So Add more agent to Customer Premium Cert skill group seem to be the right approach and modify voice phrase if necessary.