Evri complaint: Wrong parcel delivered. No response to phone/chat contact

I sent a parcel to a friend for their 50th birthday from the post office, who advised I use EVRI. The parcel was apparently received at the correct address but was actually an entirely different parcel that is nothing to do with me. It had the correct address label that I completed attached to it. I have no idea what has happened to the original parcel (although it has my name and address written on the side of the parcel). All attempts to resolve this by contacting EVRI are concluded with the message that my parcel was delivered and contact the sender (I am the sender!). I have left several messages outlining the issue and have not been contacted.

I do not know if my original parcel was stolen and this was intentional, or if the parcel label became detached and mistakenly attached to the wrong parcel. Either way I want the original parcel to be delivered to the right place, returned to me or to be refunded for the cost of the contents. It is very frustrating not to be able to speak to a human who can understand the complaint, which is not straightforward!