Bigpaw

If we buy the package online and once onboard (embarkation day) find we can buy it at a cheaper price, can we go to guest services and cancel the online package and buy the package at the cheaper price? For example, right now we can reserve our deluxe drink package for $78pp (x2) = $1092. It seems that often on the day of embarkation there is usually a BOGO offer for about $84 + 1/2 off for second person. That would come out to $882, a significant savings.