Parcel sent from UK and sent back to sender - lost at custom border

Hello, I have sent 3 months ago a small parcel from UK to Belgium via EVRI. They did an error on the labelling and Belgian customs were asking for a very high custom fee which I refused, so the parcel is sent back to the sender - me. The parcel was lost for a while and I had to find it myself at the customs. Coming back to the UK, the carrier lost trackng of it for a second time in a row, th parcel arrived in UK on the 19th August, and after several calls with Royal Mail and Customs, my parcel is more than probably again at the UK custom border (probably with a wrong labelling again). At this point, EVRI doesn't feel interested anymore to help me find my parcel and they are absolutely helpless. I would like then please to find my parcel back myself at the custom border, I have all details, references, name on it etc... Is there a way please to contact UK custom border about this issue? Many thanks

Hi,
Sorry, we can only answer HMRC questions on this forum.
We can only advise that you contact your courier or royal mail about missing parcels.
Thank you