Marriot crystal towers refuses to refund me and is getting double payment

I had a work trip booked and the hotel wouldn’t let me check in without confirmation from the office so they made me pay my first night and would then refund me upon receiving confirmation from the office. While staying there they got confirmation for full payment yet they still haven’t refunded me. I keep calling and they keep saying they will get back to me. In effect they’re ****ming me as I have paid and so has the office!!