I am brand new to the forum and am in need of technical advice. I reside in East Fife , Scotland.

2016(February) L494 SDV6 has a persistent fault which my Land Rover garage and personal mechanic friend cannot fathom out.
I have had the car since March 2020 now having 142700 miles on the clock.
Constant turbo overboost fault P0234-77 reported on a regular basis.
DPF was changed only to be replaced again six months later.
Right hand turbo replaced at the same time , however I still have the problem frequently.
Switches, pipe clusters have been replaced but my respite has been short.
Any suggestions welcome to try and solve this problem otherwise the car will have to go.
I love the car but at 77 I have had enough.
I am desperate to solve this and know that it probably isn’t a major item and someone can enter into a dialogue with me and allow me to enjoy the car for future years.
I would appreciate any interaction.