No service whatsoever

My parcel was consigned to dispatch on 2 December 2024. Today, 7 days later, I have still not received the parcel, no message about the delay, nothing. I have been trying to call centre with no success. When I check this morning, apparently, the parcel has been returned to the sender. I have no idea why or how. This was supposed to be a gift for someone, now I don't know what to do.