Not worth the paper it is written on!

The car has been running badly recently. The inlet tract had been choked with oily coke. It seems that my ‘full service history’ as dutifully stamped by my local main dealer is not as full as it should be. It appears that some filters have never been changed during the life of the car. An independent source has said that this could be the cause of the contamination of the inlet tract. I feel like an old friend has been poisoned.