Voting is a Secret or Not?

i receive a customized mailer from PAP to request us to vote for them, Isn't that a breach of personal data & unfairness to the opposition?

i thought that our vote is privacy and noone will know who you voted for.

still have my Full name in it but as you can see my mailer i have blurred them.

but SDP Dr Vincent Wijeysingha said on his rally that "popular belief, the serial number of a ballot paper is not used by the ruling party to track voters, but to make sure no one adds extra ballots. The ballots are then stored and burnt after six months in the presence of candidates."

well and again, you wont know if its true or false. i still got two more days before polling day to think who to vote for...