First of all, if both previous & new owners do not perform any update and registration, how would the system detect/know that there is a transfer of ownership? How would the VEP RFID be void/cease?
Next, how can previous owner update the ownership status/profile in VEP portal? To update ownership, probably new owner info must be provided. But in case you are selling car to used-car dealer, it is a company. you won't have new owner's details to update it.
Furthermore, how to de-link the TnG card with VEP tag? Otherwise, if new owner continue to drive thru CIQ gantry, the charge will automatically link to previous owner's TnG card?
Yes, the VEP is tagged to the car and is not transferrable. When the vehicle is sold, I believe the validity of the VEP RFID would automatically cease. If you are the owner of the vehicle that is being transferred, you must update the ownership status of your vehicle. If you are the new owner, you should apply for a new VEP and ensure the ownership of the vehicle is updated by the previous owner.