i'm willing to believe it works, but on my only try with a UK Visa I got a penalty rather than a discount. Everything fine at KLIA, but the transaction failed when I tried to exit at Sentral: had to queue to pay again for 20 minutes at the sole customer service window open. So I paid twice and suffered a long delay. The company later verified the first payment, and finally refunded the amount to my card.

I suggested they should take the hit from technology failures, and let passengers through in those situations. But it seems that's quite against their concept of of winning customers' hearts and minds.