[Engine] Head gasket ?? 2.0HDI

[Agri_Yuppie]

Hi
My 2002 2.0HDI died last week, The EGR valve got stuck and she went into limp home mode. Garage sorted this out, when they ran it up afterwards, they discovered air bubbles appearing in the radiator header tank !! They bled the cooling system. Same result afterwards.
They put a tester on header tank, this showed Exhaust gases in coolant !! So it looks like either head gasket going or a cracked head ?? There was no water in oil or oil in water. She doesn't use any water. Engine runs ok. Is there anything else it could be ??
( I trust them, they don't go looking for work like that)
Any ideas on rough cost to change head gasket Please.
Many Thanks