Just sharing my experience.
My old STB kaput. Bought second hand from one of the forumer.
Call 100 to unbind my old STB and new STB as per guide posted in this forum. Sadly the CS guy like blur only and insisted it cannot be done over the phone. He repeatedly said that TM technician must come to my house to setup. After about 10 minutes I hang up.
Try TM live chat. Type my intentions to unbind both STB. Less than 5 minute
Done. Can enjoy the new STB. Seems live chat CS better technical understanding.