Sounds like typical lbs mechanics/employees. Probably didn't have the brakes adjusted correctly and since they let a customer get on a bike and test ride and almost kill herself they aren't going to accept responsibility so they make up some excuses and hope the customer is uneducated and will believe that it's common for disk brakes to need 3 weeks to brake in before they will stop your bike. "Just jam your foot against the back tire to stop. That's what everyone does for the first three weeks!"