Personally, I would not terminate.
By enforcing your own policies consistently you have the ability to completely resolve these issues.
- Parent arrives late: charge fee.
- Parent brings sick child: refuse entrance at door.
- Parent does not pay tuition: fill their slot.
- Tuition is not attendance based: No pay/No stay
- Ignore parent temper tantrums as long as they pay and follow policies
If your policies are not important enough for you to enforce how do you expect them to follow them? Don't make policies you won't enforce.
You are the only one with the power to fix this.