Hi Andrea

I'm sorry I don't have a specific software recommendation to make as I haven't ever had the need or opportunity to research this kind of thing, but it does sound like an interesting challenge.
I ran a Google search using your keywords 'Automated reward program software' and see there are quite a few options out there but in reading a bit more about what those kinds of services offer I started to wonder if maybe she needs more of an e-commerce solution with this type of feature as a built-in option. With that in mind, I might suggest looking for a shopping cart system that allows for rewards program or BOGO customizations.
I don't know if that helps at all... just thinking out loud about different directions you might take to track down what your client needs.
Please do post back if and when you find something that works, I'll be curious to learn what you decide on!
(And hopefully, in the meantime, someone else might jump in here with some ideas...)