Booked my imac into the genius bar at Bluewater as it has an intermittent power failure issue. Had a small wait but then was seen by someone that knew what they were taking about. They narrowed it down straight away to a hardware problem in the power train and ordered possibly needed parts right then. They said there's be a call in 3-5 days to say how it was going and then it should be ready in 7-10. Got a call after 3 days to say the psu and logic board had been changed and it was nearly ready. 5 business days and it was ready for collection. Collected and the fault was gone first time. Excellent service throughout. John Lewis had been trying to fix it for 3 months.