Add an extra feature in appointment+

Hello,
Appointments+ is really a great plugin to manage appointments and reservations.
I'd like to suggest an extra feature needed by many customers and businesses (sports centre, Spa center, etc...).
I'm sure you could sell more A+ with this feature built-in the plugin.

As sample, imagine you have a Tennis Club.
You offer different way to pay and reserve tennis courts.
1) By hour (10$)
2) 12 hours (12 times 1 hour) ==> cost = 100$ (2 extra hour free with the package)
3) Unlimited with an annual fee (1000$).

The idea is to allow members to buy those packages on line (or offline directly in the tennis club).
Option 1) works already

To manage option 2), I imagine to be able to buy the package and give the possibility to the member to reserve 12 times a tennis court without having to pay again. The system would subtract his account after each reservation. When his account is empty, he have to buy a new package.

To manage option 3), an administrator encode dates from: to: to allow the member to reserve freely any tennis court he want.

If you like this suggestion, please like it.
Dimitri