What service might I use if I needed to fulfill the following requirements: 1) Say I already have a customer -- he already paid a signup fee and we charge him

What service might I use if I needed to fulfill the following requirements: 1) Say I already have a customer -- he already paid a signup fee and we charge him monthly, so he's already put in his credit card information. At a later date, we need to charge him for something other than his monthly subscription fee. This is something he can do himself by logging in, but also something the site administrator needs to be able to do by selecting his account and clicking a button. In this case, we do not want the user to have to re-enter his credit card information; we want this part to be seamless. Is there a payment API that can do this -- random one-off charges against an existing account without the user having to sign into the third-party service himself? 2) Is there a service that charges bank accounts directly -- as in they enter their bank account number instead of a credit card number? Other than PayPal --they seem to be the only one that does this.