Military PCS Cancelation

My husband and I recently received orders to PCS move overseas for 3 years. Because of this we have to cancel our service as AT&T does not provide coverage there. We each have installment plans that we entered into over a year before receiving orders and we both traded phones in with credits to use towards paying for the new phones. Customer service is now telling us that because we are canceling early we have to pay the full value of the phone and the remaining credit from the trade ins will not be applied or refunded. Shouldn't this be covered under the Civil Service members relief act? It seems to me that this is an early termination fee and we are being penalized for something that is out of our control.