def customer_item_quantity_overage(item_code = nil, code = nil)
      over = -customer_item_quantity_remaining(item_code, code)
      over = 0 if over <= 0
      over
    end
def customer_item_quantity_overage(item_code = nil, code = nil)
      over = -customer_item_quantity_remaining(item_code, code)
      over = 0 if over <= 0
      over
    end
The overage amount for the given item for the given customer.  0 if they are still under their limit.

item_code must be provided if the customer is on a plan with more than one item.

code must be provided if this response contains more than one customer.