Yep backing up your files is your responsibility and should be done at least every other day if you are doing a lot of file changing. Less often if it's only a random change in things here and there. I do weekly backups of my system to an external harddrive so that this type of thing can't happen again to me either.
Truly it's good practice to do so and it's not CC's fault that you completely lost that file if it was an update to the file, you should have kept a backup that you can go back to. And once again I still don't think the program is the issue here at all. I don't think that the problem was related to CC, but it did lose the file which would happen to anything you used if it crashed.
If you change settings on any program at all and it crashes before you shut down you will lose every single setting you did. That's normal when things crash so it's not uncommon that you would lose a page you have created if it crashes before it's saved, what is uncommon is that the crash would cause a blank page. That part may be something that messed up the program when it crashed, but I don't think that initial issue was caused by the editor at all.
Either way, I will hope that at this point on you'll keep backups on another drive or uploaded periodically so you have them to fall back on. If the page was an edit and not a newly created page then you still should be able to get a backup copy from your hosting company should you need it bad enough.
Other than that, we really don't need a step by step description of your support situation. Just because you filled in the blanks doesn't mean the person you're talking to in support got that information. Give them a break already and let them help. IF you cannot do what they need you to do, don't come bashing them for it here. You're the one choosing not to let them help you not them.