Drain trouble

What promised to be a mad hot day got worse when Mr Patio lifted the manhole cover to fit the new recessed cover and found the awful liquid level just 9" from the top.
We borrowed drain rods but they weren't long enough. Went to Screwfix and bought another set and were then certain that the problem was the main sewer not our pipe.
Chased and threatened the water company who reluctantly upped the priority and got a man with a van out this afternoon. The owner of the field next door showed us where the manhole was on the main and on lifting the cover we could see it was blocked.
Our man fired up his water jetter and cleared it out then recovered the culprit, bundles of nappies and wipes and worse.
Are people totally stupid?
If that had blocked a week later we would have had raw sewage all over a brand new rather expensive patio.