Which credit card processing systems out there allow the ability to modify the terms (price, bill date) of individual recurring billing subscriptions?

Paysystems.com allows you to edit the recurring transactions, but not the "bill date".

Originally posted by Aussie Bob
Paysystems.com allows you to edit the recurring transactions, but not the "bill date".

So just the monthly price each individual client pays is changeable?

I think authorize.net has the best built in features with modernbill. You can set the recurring billing on a set date, or on the invoice due date.

Originally posted by mushrew
So just the monthly price each individual client pays is changeable?
Yes. See attached image -