A2billing auto refill with certain amount based on threshold.

Hi, I am looking for professional help with a customized auto refill. The feature we would like to add is to auto refill the account with certain amount every time the credit reaches to a certain limit as defined in the customer profile ( threshold ).Admin should be able to define the threshold to trigger the auto-refill process. Based on the quotation for above task, we may as well be interested to add credit card processing to auto refill as well. Thank you.