A few month ago I went to put my car in for a pad change and on driving to garage the ECM light came on and I noticed a distinct cut in power. Luckily the garage was only at the end of the street and a friend who works there diagnosed it for free. Within seconds he said it was the Coil Pack 3. So they replaced it at a cost of £70.
2 weeks ago same symptoms same fault but this time i was a bit further from a garage (different coil pack) and as I am covered by the AA I just gave them a ring. They came in 20 minutes and behold carried Coil Packs with them

Now....... Last week a third pack went. this time i bought 2 from ebay for £20 and fitted them myself as after watching AA guy realised how damned easy it is.
Only one more pack to die now but i have a spare in the boot. Aparrently quite a common fault after 30k I'm at 32k now.