The top hoses have been replaced with silicone. I’ve also had a smoke test done and found nothing apart from a hole in the air supply tubing to the turbo which I’ve also replaced. 2010 MY Vogue SE TDV8 3.6 Stornoway Grey- fully loaded

So the code shows a problem with the boost, you’ve got a remap which will likely have altered boost. If you are certain that there are no leaks on the boost side then I think the advice you were given by the tuner looks good.
I’m a dinosaur and generally not a fan of remaps, no doubt there are some excellent ones but there are also some poor ones and sadly it is often the “next” owners that face the problems

To be honest, I’m not bothered about a remap. I bought the car assuming it was standard. I’m sure the TDV8 is quick enough in standard form and my main priority is towing.

So how do I remove the map and put it back to factory? 2010 MY Vogue SE TDV8 3.6 Stornoway Grey- fully loaded

The PO23d code is normally a crack on the inlet manifold drivers side. A smoke test would normally show that up though. Unless it's only when it gets hot and the plastic expands. Try the soapy water test. Current 2007 TDV8 Vogue Buckingham Blue

Sometimes it faults as soon as I leave the work car park so I don’t think it’s down to getting hot and expanding. Then it won’t fault for days. 2010 MY Vogue SE TDV8 3.6 Stornoway Grey- fully loaded

Sometimes it faults as soon as I leave the work car park so I don’t think it’s down to getting hot and expanding. Then it won’t fault for days. 2010 MY Vogue SE TDV8 3.6 Stornoway Grey- fully loaded

I would expect whoever you spoke to about the current remap would be the way forward to getting it set up with a standard map