How to deal with a friend who is using me as a time pass?

She will phone me when she is driving to Walmart talking about nothing and she will tell me she needs to hang up but then will tell me not to go anywhere as she will phone me in 20mins time. I feel angry by this as she seems to think I have no other plans and demands my time. Why doesn’t she ask me if I’m free instead of scheduling things in my time

How to deal with a friend who is using me as a time pass?
Post Opinion