We're typically very fair about how we charge against the hours. If the ticket requires a fair bit of research and bug fixing, no we don't charge you for the hours. A recent notable example involves a customer who came across a really nasty bug with the mobile IPSEC code. CMB and a couple of the developers have put approximately 30 hours into diagnosing, coding and testing the fixes, but the customer hasn't been charged anything like that. We only assign time to a customer's account if we're actually working directly for the customer during that time.
The other side of that, however, is that if the customer expects a support technician to be on the phone with them the entire time, while they try and figure out a completely unrelated problem, then yes, that time will get charged. To date, we've had a great track record with very satisfied customers and as far as I know, we've not had to refund a single customer based on a quality of service complaint.