Totally agree re. sh1t SAs in London - I was in the brompton rd store the other day, asked when they were expecting the Rock, after about 10 mins trying to explain the bag they finally got the look book out and established they'd ordered it - i was like 'so it is called the Rock then?' and they were like 'yes it appears so' after denying the bag even existed!!! This was 2 different SAs.
Useless. But yeah in my experience the guys in Harrods are much better, there is a french guy in the main clothing and bag boutique section (not the shoe) whose name I cant remember but he is awesome. In general though London Chanel SAs are totally useless and never know anything about their stock.