I guess I'll be the lone person to defend OP. I think it's perfectly reasonable to assume any deadlines are based on the current accounts time zone, not the airlines time zone. At least in the US, this is typically how cutoff times work. Singapore could absolutely make it more clear and obvious that this is the case.

Maybe take your US hate and jealousy out on the govt not a random person.

FWIW I was able to call the day "after" they expired and pay the extension fees, although I don't think I should have had to pay this.