Where is the MTR customer service in the HK airport?

In my previous travels to HK I buy my 2 single journey travel pass at the MTR ticket center in the airport. However, I see it is cheaper online. It says that I should collect the ticket at designated collection centre: Airport Express Customer Service Centre of Tsing Yi, Kowloon or Hong Kong Station. Is there a place in the airport where I can collect my tickets purchased online?