Actually we drove with a group and took a travel bus to get to Sentosa Island. But for the need to go to the vivo city mall which could not be done together with our group, we had to find a way to go to the vivo city mall while purchasing monorail tickets was not available from sentosa island. Luckily the purchase can be made through traveloka. Thank you Traveloka for being the solution and very easy for us.