My aunt tries this. She doesn't call on my cell phone, but tries to give me a list of things to pick up for her when we go. Mind you, she does this everytime she finds out we are going across the border, so it doesn't surprise me she tries it on Black Friday too. I just tell her I can't promise anything, cash up front (taxes too!) and if she pushes it, then I tell her no, I won't have room in the car, nor the time to go looking for it.
As for the handicap sticker, after years of playing the drive around and wait til she got a close spot, or have us drop her off at the door, she FINALLY applied for and got her handicap sticker! We joke and tell her that is why we bring her along . Makes her feel useful;) or she will guard the cart for us (she walks with a cane, the LAST thing I need is her trying to get in the middle of a mad dash).