Sorry to hear this Mike!
I have in the past and still sometimes, a serious issue with my post and I believe the problem lies with the sorting office, well in my case anyway. It so happens there’s a street/culdisac within 15 miles of my culdisac that so happens to street name as mine and a very similar postcode and our post gets mixed up. The problem I found was companies/council use autofill, that misses the name of the village/area within a town and what would normally be the second line of your address.
Most of my post is now upgrraded to recorded delivery, which srangely the problem does not occur or I arrange to collect if local. As @joss has said, arrange with your local council depatment to leave it at the front desk and you will collect it on x day.
There is also a possibility that their is someone with your main or local sorting office that knows what they are looking for and has alteria motives!