We started having this problem a few months ago with shopping carts. Yikes! I think (hope) it is a phase. The only solution I have found is to use the comfy strap (that padded seatbelt thing) and secure her tight. She is not happy for a few minutes but decides it isn't worth it to put up a fight. However, I still have to shop very quickly and sing every children's song in the book... I hope this doesn't last too much longer for you. :)