private void WithdrawMoney object sender ElapsedEventArgs var withdraw

private void WithdrawMoney(object sender, ElapsedEventArgs e)
        {
            var withdrawnSum = 0.0m;
            foreach (var v in _parking.Vehicles)
            {
                var defaultFee = Settings.Tariffs[v.VehicleType];
                var withdraw = defaultFee;
                if (v.Balance < defaultFee)
                {
                    var missingAmount = defaultFee - v.Balance;
                    var penalty = missingAmount * Settings.PenaltyFactor;
                    withdraw = (defaultFee - missingAmount) + penalty;
                }
                v.Balance -= withdraw;
                _parking.Transactions.Add(
                    new TransactionInfo()
                    {
                        PassedAt = DateTime.Now,
                        VehicleId = v.Id,
                        Sum = withdraw
                    }
                );
                withdrawnSum += withdraw;
            }
            _parking.Balance += withdrawnSum;
        }