It has been reported on this forum that you can deliver cash to the general office on ship upon checkin to have the amount reduced or totally averted. I have no personal experience
No snark from me, I don’t allow large credit balances on credit cards, it just seems foolhardy unless one has a specific need
I often email HAL these questions if the cruise is a few months away. Usually the emails get a thoughtful response as you are being given a written record.