Advice on trying to get builder to rectify poor garden

Folks, apologies for the long post.
Moved into a new build estate circa 16 months ago.
Back garden had grass seed thrown on top of what looked like poor soil due to number of decent sized rocks that were visible including the odd piece of litter appearing out of the soil!!

When speaking to foreman about garden and its poor growth he would say give it a year and stick a fork into the soil. I did all that and joined here and got very helpful advice.
Following advice on here and advice from a professional I had out, the following is everything I did at some stage or multiple times
1. Aerate regularly
2. Added sand to improve drainage
3. Raked the moss/thatch out
4. Added fertilizer
5. Added lawn feed
6. Added grass seed
7. Religiously got down on my hands and knees and took out weeds, creeping buttercup & clover. I now have couch grass in my garden following identification through a post on here.

Aside from all the above, most of the soil has moss sitting on top, there are patches where it is just moss in the garden, there is a part in the middle of the garden where it pools rainwater days after it rains, I have unearthed large stones beneath the surface as I aerated the lawn, there are a couple of patches where grass won’t grow and the area around the back of my garden is constantly wet as their is a neighbouring estate on an incline whose back garden would face onto and down into our back garden so their garden likely drains into ours.

From all the advice on here, it is clear the soil is poor, it is badly compacted, poor draining and the best advice would be to start it all over from scratch. Remove everything, bring in proper sand, topsoil and plant seed again.

It turns out a few neighbouring gardens complained to the builder and had their garden taken up and replaced with new soil and rolls of turf.

Builder came out two months ago to view garden and took pictures. Then they went dead silent and I have chased them non stop for an update since. Eventually they got back to me to say they will send someone else out to review it as the last person to review it has left the company but he said my garden was fine - which is hard to fathom when there was a pool of water in the middle of it even though it hadn’t rained in days.

The fact they replaced some neighbours gardens who according to them mine is in worse state and are practically refusing to replace mine has me extra determined especially as I put a lot of work in to improve it and it is a losing battle. Also, I briefly spoke with a legal professional who said I could have a case for a breach of contract as the house I bought based on what I was told and seen in the show house is not what I was delivered, it would mean going down the small claims court route.

The grass has not been cut for a few weeks now but I think if they come to inspect the longer grass may hide some of the issues. Is it worth my while cutting the grass to show the poor growth, the moss on the soil, show the damp soil and pools of water but cutting the grass will make the couch grass less transparent ?