You can never "pay in advance" and then request a refund, that's how paying in advance works
The hotel gets paid in advance (except in some cases - e.g. in Germany where many "pay in advance" rates actually aren't charged until arrival or no-show) and then refunding you and getting Accor to pay the balance (which is basically what happens behind the scenes when you "pay" with points) would be a nightmare in every way.
As discussed, if there is a "coins" symbol next to a rate, you can pay with it using points. You will also be prompted to use points - if you have at least 2000 - when proceeding to payment in case of a prepaid rate.