function __construct($purchase_id, $billing_data)
 {
     parent::__construct($purchase_id, $billing_data);
     $this->setAutoBillOutstandingAmount();
     $this->setBillingFrequency();
     $this->setStartDate();
 }
 function __construct($purchase_id, $billing_data)
 {
     parent::__construct($purchase_id, $billing_data);
     $this->setAmount();
     $this->setGCFee();
     $this->setOwnerFee();
     $this->setCommissionFee();
 }
 function __construct($purchase_id, $billing_data)
 {
     parent::__construct($purchase_id, $billing_data);
     $this->setAmount();
 }