You really need to call them and speak to a live person, this is too important and must be straightened out. Ideally you needed to speak to someone last Tuesday to try and advocate for either an extension of document submission (unlikely as they need enough time to go over what you send them in order to prepare) or to reschedule your date. Not sure what city you are in, but my experience with the Toronto office is that it was very easy to get someone on the phone and they were very helpful. You have someone there managing your file, this is who you want to try and speak to. The phone number should be there somewhere on correspondence you received from them, or is easily located online.