Here's my suggestion
Hi airgirl,
Since it is landing that is of most concern to you, and since landing constitutes a crucial and compulsory part of every flight, I would say that it would be worth doing another hour or two.
I suggest, however, that you should do this extra time with a different instructor, someone with whom you have never flown before, who should be there, as Dublin Pilot suggests, just for the ride. Why not take the Chief Flying Instructor, then you would have a second opinion from someone who carries real authority?
Quite apart from being there to intervene if intervention should become necessary; (it won't), this instructor would be able to give you a second opinion on your flying in general and your landings in particular.
Let us all know how you get on.
Good luck!
Broomstick.