Might be worth doing a forum search on replacing the Bluetooth module. My recollection is that this has been a frequent issue - mine is hit and miss, but I can live with it at present.

EDIT: Try https://www.freel2.com/forum/topic11565.html?highlight=bluetooth 2005 D3 2.7 Auto
Previously:
2010 MY FL2 TD4e GS - Now gone at 199,500 miles, about 135,000 of them mine.
‘93 Defender 110 200TDi CSW
‘87 Defender 90 4 cyl Petrol
‘83 110 CSW V8 - best ever!
Range Rover 2-door V8 (not sure of year - 4-speed box and vacuum diff switch)
Series III SWB Diesel