Service charge non refundable 5min after erroneously making a booking

I downloaded the airbnb app and had a look at the houses available. While navigating the app it asks me for my credit card details and I insert happily as usually these details are needed for booking and surety. Next thing I see a message to say my bookings been confirmed and accepted by the host ascend next I see an amount taken frm my bank account iro error booking. After 5min on the not so user friendly app I figure out how to cancel the booking and it again notifies me that an amount wil be refunded but this amount is now R893 short as "service fees are non refundable". Does airbnb make provision for errors that happen with novice users or do they just prefer to practically ***** money this way from u suspecting users? I want my R893 back now!