I bought some at the airport last week, and was given the wrong shade by accident.
I needed Light Plus and was given Medium Dark.
I went into a MAC shop here to see if I could exchange it and they gave me a customer service phone number.
I rang them (Didnt realise they were Estee Lauder!) and a lovely lady took my details and told me she would send out the correct item, and not to worry about the one I had bought-she said to discard it!
(Full marks to them for Customer Service though)
Seems a bit of a waste to chuck it. All my friends are pale or pink red faced people so can't give it away in RL.
So if anyone would like a brand new unopened box of MAC Mineralise Skin Finish powder, shade Medium Dark, its yours if you pm me your details.