As others have posted above, when you choose a points & cash booking, you are actually doing two things. Firstly you are buying some points for cash, then you are making a reservation using all points.

You can't get a receipt for the room because you have paid with points not cash.

You can however get a receipt for the points that you purchased, as this is a normal transaction.

I don't think you have any chance of reversing the CC payment.