Parcel delivered to stranger and opened by third party despite PIN required by courier

I received an SMS to say that my parcel would be delivered in 5 minutes. Half an hour later there was no sign of The Courier Guy yet, and I rep**** to the SMS but received no answer.

I then contacted The Courier Guy through their Helpdesk Chat facility through their website before 5 in the afternoon, and received a message to say that an agent would be with me shortly. Someone only rep**** at 8 the next morning.

When it didn't look like I was going to receive a reply on their website, I contacted them through their WhatsApp number and was told that my parcel was delivered, with a photo of a waybill on which nothing could be made out. I asked who it was delivered to, and where, because none of the people living in this house have seen The Courier Guy that day. The answer I received, was that the PIN was sent to my number. I rep****, saying that The Courier Guy obviouly didn't ask for a PIN, since no one at my address received my parcel.

Still not knowing who my parcel was apparently delivered to, I phoned my neighbour after a while and asked if she perhaps had a parcel for me. She said that she received a "blank" Courier Guy parcel (no waybill, no name, no address... no indication at all who the parcel was for) from a guy feeding their dog that day, and since there was no info about who the parcel was for, they didn't know to phone me, and then opened it! And the contents were confidential!!

I told the person on the other end of the WhatsApp chat that I found out the parcel was delivered to someone I didn't know, who was at my neighbour's house at that time. The consultant proceeded to tell me that the parcel was delivered to MY address, at which point I AGAIN told them that I only received my parcel half an hour earlier from my neighbour (this was at about 8pm at night), after tracking it down myself.

I sent photos of the opened parcel as I received it, and was then told that my query would be escalated to the relevant department. It is a week later now and I have had no further feedback.