The starting point. Unfortunately, between taking this photo and actually commencing the kludge one-or-more cats had jumped up onto the replaced top. The shonky side couldn't cope with that level of impact and strain, and the front upright had been tilted diagonally forward, pulling all the slats out and tipping the lid into the bin. The cat must have made a most undignified descent...
First, give the really shonky side some structural integrity by adding some foraged plastic mesh. Attach said mesh using cable clips because you happen to have some. Attempt to wiggle at least some of the slats back into (approximate) place.
Attach a couple of brand new slats/struts to the bottom of the inside (not shown) of the shonkiest side and the back, and one to the outside of the better side. Use screws because attaching that way puts less percussive impact on the remaining wood. Don't enquire as to why not the inside of both sides, I can't recall my thinking but it probably seemed a good idea at the time!
Cast an eye over the shonky side and add a bit more foraged plastic mesh to the top. Decide to do what you'd previously done to a slightly less shonky bin and line the inside, to about half way up, with top soil and commercial potting compost bags. Something else that seemed like a good idea at the time but time will tell (the first bin to have that happen to it will be emptied next autumn).
Stand back and admire the view!
Notice that, while you were wrangling the shonky side back into some attempt at structural integrity(?!?) that you'd not managed to align the front post correctly. Emit further Language. Sigh resignedly. Slide and wiggle the front slats, or rather as many of them as still have some goodness, back into place.
Make a note that you need more front slats - they need to have the ends routed so they slide in and out of the slots. You know who to ask and you have a scrounged pallet. Thank the deities that your replacement car has rear doors because that's probably the only way you're going to get a pallet into an Aygo!
The End.