I agree with what the other posters have said about the MAC shop at Westfield - I can just about put up with the security guard on the door restricting access, as I understand that it's a small shop and the staff can only deal with so many clientelle at a time, but I have consistently found that once I am inside, the staff try their best to ignore me
As a previous poster said, bright yellow or blue hair, copious piercings and tattoos and makeup that looks like it's been applied by a 3-year-old aren't appealing looks either, so the appearance of the MUAs didn't inspire me with confidence. Most of what I was after was out of stock, so I ended up coming home and ordering online without the benefit of testing first, and to top it all off, the security guard refused my 18 year old daughter access when she wanted to come in to join me in the store.
I wouldn't be surprised if the store is losing money hand over fist to the much more pleasant Inglot store opposite.
I recommend that MAC customers try Brent Cross instead, or go into central London.