Are my Hedges Fixable or Fecked?

Long story short, we got a major renovation done after buying a house. The hedges were oit of reach essentially due to vans, skips and refuse for about a year. They seem in a really bad way and the plant medicine stuff (Westland Buxus Feed/Protect) doesn't seem to be making mhch difference after a couple of weeks.

I'm after doing a major overhaul in the lawn and driveway with some help from advice from here. I wound up digging up literal multiple tonnes of random crap from underneath the lawn (a combo of mud, stones, tiles, cement, clay, and other crap), and have a large bin of mulch from the old owner in the back, but I know sweet feck all about gardening so was wondering if people think it is best to

A) Fix these hedges (and if so, how?)

Or

B) Cut down the hedges, run them through my wood chipper, buy some elevated planter boxes, fill said boxes with all the mulch and other crap plus some new soil, and use that to form a row of smaller hedges/plants that would still be a similar height (eg for privacy, there's a public lane fight in the other side)?

One part of me would like to keep the original alive, another thinks the latter might be better in terms of being more manageable and flexible, but really I don't know what I'm at so just looking for suggestions either way!