Robinsons, Isetan, Tangs
or go to any of the SaSa stores..
up to u.. :)
those are the companies' name...
if u r student in NUS or NTU, u can go to Boonlay's Jurong Point shopping centre.
there gt SaSa.and other shops that selling cosmetics,but i m not sure gt Lancome or not
or u can go to Bugis or Orchard, u will be able to find the outlets of Lancome in any shopping centre