I haven't heard of this problem before, and I suggest contact Airbnb immediately. As far as relying on IB, I think if you don't hear from the host when you book it is a bad sign. New hosts have to have IB, and they are sometimes unaware of what happens when guests book them and it all comes as a surprise. When you book by making booking enquiries or requests, you will have communication with the host first and will know everything is going to plan.
Find a new place, if the host you were supposed to book with is unavailable. Check if your account has been charged or not. Good luck, I see you are a first time user of Airbnb and I hope it will all work out better soon, it is a great place to find accommodation. The best, in my opinion, but I don't use IB if I can help it.