It's not so many years ago , I would have expected to buy a motorhome for thatMercedes say
The turbo waste gate valve is stuck open
There is delamination inside the manifold (a flap has broken off) resulting in constant back pressure
Possible issues with catalytic convertor and or DPF
Parts not including new cat or DPF £1950 + VAT
Fitting they cant quote till they do it due non standard access issues, however on a slightly positive twist on that, they think it can be finished this week, so no more than 4 days labour at least
In fact the one we did buy before our latest only cost £500 more and took us around France , Spain and Italy without a fault, progress eh.