Mccarthy
Oil leak

I booked my car in at Mccarthy VW Menlyn yesterday for oil leak after it was serviced months ago and the Service advisor called me and say that the technician said that the oil leak is not because of the service, it is the vibration of the engine that cause the bolts of the oil pump to get loosen.
No tell me if the engine vibration can do that to the oil pump, what else can also loosen?

Please respond.