Since we packed the free of charge package & charge package together, therefore the correct freight cost is USD$120.
About the remaining cost USD$100, we will deduct the cost from your future charge order.
I suggest that you may apply for a DHL account for HSM.
We use YCM account for the free of charge order, and you could use HSM account for the charge order.
I thought it could make the accounting much easier.
Sorry for any inconvenience.