Poor Scheduling

My manager had me stay a half hour overtime because he didn't schedule enough people.

 On my way off the register, some woman asked if I could help her in Cosmetics. Which I stupidly agreed to. I met her over there, and she showed me some make-up. Then she handed me the kind of remover she wanted. She asked for the aloe vera and when I told her where it was, she just stood there until I walked her over there. And she handed me the bottle she wanted. We went back to the make-up and she stood there until I pointed out exactly what she wanted, and I had to hold that too. FYI, she had no apparent disability. I tried to tell her where the Advil was, and then she repeated "Aisle 9", like I just said "Uzbeckistan". She needed some insoles for her heels, and when she asked for help finding out which ones, I told her to ask the pharmacist. Then she looked down to aisle 9 like the walk was unbearable. I ended up walking over there with her because her stupidity was unbelievable that I felt like I should help. Apparently she couldn't tell the difference between "high heel" and "open toe" insoles. My god. She asked if I could ring her up and I told her no because I had to go. I handed her all her stuff, which she reluctantly took.