It's probably not as simple as you imagine for them to access and reconcile banking records fast. Especially if they use a third party to process payments.
If this were me I would be making sure this gets sorted out properly as my first priority. You could easily end up on a blacklist for cancelling a deposit like that. I'd want to give them that statement fast to make sure they believe me before worrying about anything else.
If you think you need any help sorting it out, shoot in a complaint form
http://www.sportsbookreview.com/sportsbook-complaint/