Overtime charges.

[Play and Learn]

Grace period of 5 minutes, then $1/minute up to 20 minutes. After the first 20 minutes it then becomes $5/minute.

IF they contact me early enough to say they're running late (ie snow storm, and there's an accident on the highway), I'll give them a 10-15 minute grace period, and then after the 10-15 min, it becomes $1/minute for 10 minutes, then $5/minute afterwards.

Then....if they become to abuse it, they get a strike (I have a 3-strikes you're gone policy). It's a great way to regulate the system.

Good luck!