There is a critical bug with Amelia with Backend Package Bookings that is extremely problematic.

As an Admin, go to Services > Packages > Manage Packages, then change the dates to view older packages. If you have a customer with an old package, and they purchased a NEW package, and both are showing, you cannot book a new appointment for them. Amelia gives an error.

As a Manager, go to Services > Packages > Manage Packages, then change the dates to view older packages. If you have a customer with an old package, and they purchased a NEW package, and both are showing, it will deduct a session from their previous package even though they have no appointments remaining... This is a HUGE problem!

You need to ensure that the customer does not have 2 packages displaying when booking new package appointments for it to maybe work properly.

Video from Amelia Manager account of the booking being deducted from a package with no sessions remaining

Hey hey,

This might not be the solution but figured I should mention. Amelia Settings > Appointments, make sure "Allow booking above maximum capacity" is disabled.

It's not that they can book with other people or a capacity issue. it's that either you can't book a new appointment with a new package if an old one is showing - OR - it deducts new appointments from packages that have 0 appointments remaining, and goes negative appointments remaining