public decimal GetCustomerCurrentAmountDue(Guid customerId) { var customer = _customerDataService.GetCustomerAccount(customerId); var mowingCharge = customer.GetMowingCharge() * 2; var weedingCharge = customer.GetWeedingCharge(); var wateringCharge = customer.GetWateringCharge(); return(mowingCharge + weedingCharge + wateringCharge); }