Did not deliver the whole package

I sold a set of stroller and car seat, the only thing that was delivered was a stroller not a car seat. When I left the shop the car seat was inside the black plastic back and the yellow sticker which have the serial numbers was stocked in the car seat. But the car seat was not delivered instead they delivered the stroller. However Kim from the support team is really trying to locate my car seat but the Depo team have no sense of urgency, I am so disappointed and I lost some money regarding this. I am still waiting for my car seat to be delivered back to me cause the buy has cancelled the order