New patio is falling towards house..

Without taking up the whole this that sounds like a good option. IMHO here you have a hard fixed point, i.e. the back door, that must be the highest point and you fall runs from there. Given that'd mean lifting everything a localized fall sounds like the best option. On the aco drains, where are they draining to?

Look in terms of being shook, I understand where you are coming from but always remember at the end of the day yer not looking at a chart and a doctor telling you there's nothing they can do.

Secondly, it's on sand! Imagine if it was concreted in!?!

At this stage I'd get rid of him, getting what you can out of him by however means and do it yourself. It's not rocket science. If I can do it, trust me it's not that hard.

If you think an orange rainfall would cause problems, can you do the garden hose thing again to check?

Or is that not really a runner mid-job?

Ask a farmer a hose pipe delivers no where near the amount of water a good rain shower would bring, so if it puddled with a hose it would flood with the rain

The fall towards the house is evident against the small wall against the patio. Unless that entire wall isn't level. The fall of the entire patio is actually down towards the house. Which has obviously resulted in the puddle. So yes, it looks pretty easy to spot even without a spirit level by eye. Which is why I originally thought the entire job was shoddy tbh.

On a side note we had a company in a few months ago installing a composite door, we paid 50% up front and they did a terrible job so we wouldn’t release the final payment till they sorted it. After 3 bothched repair jobs they had to order a new door which was fitted crap again, we got so fed up with the stress and hassle and rows we just paid them the money to be done with it all. Sometimes the stress isn’t worth it!

I cannot suffer that shouting and spitting the dummy crap. It's a classic bullying tactic to get you to accept something you are not happy with.

These fellas have thick neck and no shame. You couldn't insult him if you tried. The shouting is all an act.

I'd tell him gather up his gear and be gone. He has had more than enough of your money.

Where to begin!

Firstly as others have mentioned the DPC level is critical. Normally your footpath around the house is laid at 150mm below DPC, so if this guy has laid several inches of hardcore and sand on top of this plus the patio you're in danger of damp entering the house. Drainage channel must be installed at or below DPC along the entire length, dispersing into a storm drain.

Secondly, if he's laid it on just sand that will simply subside into the hardcore after a few months and the slabs will sink and become uneven, and as others have said it will subside more away from the footpath leaving a trip hazard. It should have been laid in concrete.

Thirdly, if the rest of the garden is marshy or slopes towards the house no amount of 'flexipipe' (don't even know what this is) laid under the hardcore (if it even was) will serve any purpose whatsoever if it's not connected to a storm drain and even if it was it will block over time and any water will be slow to drain into it anyway.

Fourthly, no competent person running a company should require anything more than a booking deposit before a job is completed and references to 'big jobs' like Dublin airport should be a red flag.

IMO OP that whole patio will need to be redone unfortunately, that guy hasn't a clue what he's doing and you'd be better off to tell him to take a hike, and demand some money back or threaten to sue.