Hi, you shouldn't put up with that kind of disrespect. I charge parents $1/minute if they're late. After a half hour, that fee goes up to $2/minute. I've worked at commercial daycares and I run my home daycare with the same rules. Just because we work at home, it doesn't mean parents can take advantage of us.
Good luck! Keep the kid if she's a doll- just teach the parents the rules.