How eC treats recurring products that are not paid in any of the available options? (ie. deposit in a bank account)

Hello there!
I´ve recently installed ecommerce, and frankly I think it´s just too much for what I need. It seems far too complex. But as I need a good, solid, stable module that can manage recurring payments and scheduled reminders (and only that), using eC seemed the obvious thing to do. :)

We administrate online courses in a Drupal Platform, and the student´s payments are manually managed outside Drupal.
We have courses that can be paid in two or three (monthy) times.

So, if student A enters the course on 01/01/2008 (day/month/year), I need a reminder for his second payment to be sended on 01/02/2008. And I could have another Student, B, that starts the same course on 15/01/2008, and need a reminder to be sended on 15/02/2008.

But our students don´t pay with Visa, nor PayPal, they use exclusively Bank account transactions.
So, I basically need they to be reminded, but then they must inform us of their deposit, so we can check it out with our Bank, and then activate next course´s term materials for that student (manually).

Can this be done with eComm? I think it can be, but I´m very much clueless about this module, and don´t know were to start.

Thanks in advance for your help!!

Rosamunda
Buenos Aires