If all TiVos always respond to the default code (just like with ReplayTV) and Debbie has really programmed the VCR/0618 code, I have no idea why it's not working.
As for using advanced codes, I don't know whether they would have given you the new version of the TiVo code or not, if they gave youthe old version (which is likely) advanced codes won't work with it.
Rob
http://www.hifi-remote.com