There are two ways as told by my SA:
1. You pay full premium for new car, then baru transfer the old NCD to new car, and get refund from the new insurance coy.
2. You top up money to withdraw your existing NCD to transfer to new car. The benefit is your new car premium should cost more than the old car so your capital outlay is lower compared to option 1.

.....

Your SA is lousy as this should be a common thing and he should know how to go about doing it.