The good news is Financial Market in Singapore is very well regulated, banks and insurance companies have to disclose everything in their marketing materials. so if you take a little patience to read the fineprint, here it is

"Interest rate of 3.6% p.a. is applicable on the 12-month Singapore Dollar unfixed deposit >>>> when you invest fresh funds of minimum amount S$10,000 or equivalent in selected Unit Trusts and/or Single Premium Insurance Plans <<<<< and place and equivalent or lower amount in a 12-month Singapore dollar unfixed deposit. "

That means if you place 10K in FD and 10K in unit trust, you enjoy 3.6% interest only for 10K and have potential lost in your unit trust investment and 5% sales charge which they usually impose.

p.s. i assume the product you were referring is Citibank Unfixed Deposit @ http://www.citibank.com.sg/portal/citiwm_home_center.jsp?frameset=centerFrameset&productID=InvestmentsDeposits&frameval1=wowWorkID&path=/sggcb/english/prod/cat_land/InvestmentsDeposits.htm&framevar1=workID