they should be able to put new seals in and regas it with a dye then have a look with it running under uv light to check for leaks, the aircon compressor is the one bottom right when looking at the engine standing infront of the car, two hoses come off it, one goes through the firewall on the right hand side, the other goes through the front of the car to the condenser, radiator looking cooler infront of the engine radiator, there should be a black cap on each hose inside the engine bay they tend to leak there and you can see where oil has come out, sometime they leak at the other joints.