But if it's "y" class ticket (full economy) it should be 100 SCs.
Unless it's classed as discount economy, then it'll be 50 SCs. Does your ticket tell you what class it is?
These are the conditions I can see or this ticket booked as a flex saver dummy booking:
Economy Class
Fare type Flexi Saver
Fare basis code
WWBOXHK
Maximum stay NONE UNLESS OTHERWISE SPECIFIED
Minimum stay NONE UNLESS OTHERWISE SPECIFIED
Stopover FOR FARES WITH FOOTNOTE 4P NOTE - GENERAL RULE DOES NOT APPLY 2 FREE STOPOVERS PERMITTED ON THE PRICING UNIT - 1 IN EACH DIRECTION IN SIN.
Travel restrictions Applicable
VALID FOR TRAVEL COMMENCING ON/AFTER 01OCT 11.
Itinerary change Allowed
No charge
Cancellation/refund Allowed
Before First Flight Departure : USD100 subject to currency fluctuation. After First Flight Departure : No Refund
No show fee Applicable
USD100 subject to currency fluctuation
Earn KrisFlyer Miles Allowed
Accrual levels for flights under corresponding booking fare classes on Singapore Airlines and SilkAir: 300% for R, 150% for F & P in Suites; 150% for A, F, P in First Class; 125% for C, D, J, Z in Business; 100% for B, E, H, K, L, M, S, U, W, Y, 50% for N & Q (for flights departing from 1 Apr 12), 10% for T & V (for flights departing from 1 Apr 12) in Economy Class. No KrisFlyer miles will be earned under booking classes N, Q, T, V for flights departing before 1 Apr 12. KrisFlyer miles are not accrued on codeshare flights marketed by Singapore Airlines and operated by non-KrisFlyer partner airlines. For a list of KrisFlyer partner airlines,
Earn miles with airline partners.
KrisFlyer Upgrade Award Not allowed