Automated Repeat Payment - Protx

code needed to automate? recurring billing? on an existing protx shopping cart, based on the subscription type bought eg. monthly/yearly.? ## Deliverables in my cart I have three "products" which are basically subrscription charges of Monthly / quarterly / 6months / Annualy. I need to automate the taking of repeat payments to correspond with the product they have bought, and to take the payment after the appropriate time has lapsed