Sorry to hear that. Did you contact your Service Center and ask for the manager? Maybe they removed it while servicing the vehicle and forgot to put it back in?
I always leave items in my car while it's in for service and I've never had any issues, but of course YMMV. Actually, I just got my car back today from service and everything I left was still there (USB flash drive, dashcam, sunglasses, hat, car charger, jacket, and various tools). In my experience, the service center staff have been nothing but wonderful.