Rackspace (and others) need to call their clients on the phone in these situations. They feel it is so important that it must be taken care of in one hour, yet they use email. Not exactly fair to the client....
Still, I think it is a good idea, and one I ought to implement in my own service. The problem is that we all hate dealing with the phone, but that sounds to me like a lazy answer.
On the other hand, really, if you are an abuse problem, honestly, I don't want you as a customer.