Then you wait for the change to occur - they quote about 10 days and it will not align with your billing cycle. Wait for the next statement to arrive, where you will most likely not be credited any points at all. On the following statement, you will (hopefully) receive all outstanding points for the new program since the switch occurred.
This will see you not receiving the points you accumulated in the old program prior to the switch, in the statement period where the change occurred. These will sit in your account and won't be transferred automatically to neither the old or new program. This requires another call (see the first point).