Q: grinding noise (not squealing) when brake

If the issue did not exist prior to the work being done, then the cause of the unusual noise is due to the pads and/or the interaction between the pads and the particular finish that was left on the rotor. You might take a look at the rotors to determine if they were, in fact, turned. A guaranteed solution to the problem is to use only OEM (dealer supplied) brake friction materials and to buy high quality brake rotors (again OEM is preferred or use a recognizable name brand such as AC Delco but there are others). In quite literal terms, once non-OEM parts and materials are installed, and thus in essence an "experiment" is set up, brake noise, and other untoward effects, can be a result. If you would like a Mechanic from YourMechanic to evaluate this for you, please simply request a brake noise diagnostic and a certified mechanic will be dispatched by YourMechanic to evaluate your brakes and address all of your concerns. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.