Well, you don't, you can only hope. Cyber did say some time ago that if payment fails you won't lose your order. So assuming that still is true, worst case scenario you'll wait a little before notifying them that you now have the funds or they try to charge again. Maybe try too contact them or ask Cyber if they have tried to charge you, don't know if he can help with that though.
I've not had any emails either, since my original confirmation. I know the system has the correct address for me because I ordered as a guest, meaning I have to request them to email me a link every time I check my order.
When we placed our orders, wasn't there a checkbox on the order page to let you opt out of emails from Oculus? I checked that and have been wondering whether that's barring me from receiving any emails, not just marketing ones.
I PM'd Cyber to ask him about this a few hours ago, but no reply yet. I'm guessing he doesn't work weekends and is deep in VR somewhere, enjoying his time off!