Phantom voters are people who borrow your name and private details to vote. They can be used to tamper with election results by voting in a specific candidate without your consent.
Commonly, details of dead voters or voters who haven't registered to vote are used by phantom voters. Using the same address to register phantom voters is also common.
Immediately check the electoral roll and take a snapshot of it. Keep this as evidence for your complaint to the Election Commission.
Make a complaint to the Election Commission immediately. Select 'Pendaftaran Pemilih' from the drop-down menu. Attach your snapshot to your complaint, then inform the Election Commission that you did not file this registration.
Keep a copy of this complaint and forward it to NGOs like Global Bersih, Bersih and TindakMalaysia. They can advise you on what specific steps to take, and can lobby the Election Commission to take action.
Alternatively, your rights to vote are protected in the Constitution. You can figure out the constituency that you'll be voting in and present yourself early on election day. Discuss this with the NGOs you've contacted to see if this is a possible option.