Question regarding ShipBob

Hi, I had a small store selling products in US and used shipbob as shipping partner and kept my inventory at their warehouse, Now I want to shut down the store and take back all the inventory from ShipBob, I tried contact support but they didn't solve my problem, they are charging monthly fee. how can I resolve this issue, has anyone here had experience with ShipBob, can guide me who should I contact or where should I go regarding this issue?