I am in a similar position, I got to about 12 hours and just couldn't get the landings. I got quite depressed about it (£130 an hour to get p****d off...) My instructor realised this and we started doing navexs (which I can do) combined with circuits at other airports, so I get experience of not being able to land on other runways.
I have only done this three times but I'm really enjoying learning again and the different runways are improving my landings. I would recomend asking your instructor. You are paying after all for something supposed to be fun.