Vehicle booked for service not attended to

Book my vehicle for service twice, took it in expecting it should be serviced and still its not serviced. On the first booking the service could not be done due to the computer system being off. Took the vehicle back a week later and after being in for service for two days it is still not serviced. The indication was that they did not receive the sparkplugs, which could have been ordered when the booking was made.