I recognised the person who collected it from the buyers ring doorbell and we both live in london

The way shpock works is it uses parcel2go for the delivery and parcel2go used parcel force worldwide and they come to my house to collect the parcel and then deliver it to the given address the person who bought the item then reported to me that the package was empty and the seal broken open the buyer also managed to get an image of the person from their ring doorbell

A week ago I decided to sell something on shpock a few days ago I finally sold it for £30 + £6 delivery the day after someone came to my door to collect it, this person was from parcel2go. Now this morning the same person delivered the exact same envelope but empty what should I do? pix.pdf