z1ppy, they’re neither a VW or a diesel special but SJ Auto’s (Renault specialist, Amblecote, on the left just before you turn right up Brettell Lane) may be worth talking too. My aged Megane had a good few problems, some of them diesel based, and they fixed them with minimal fuss. It’s a bit rough round the edges as is the fella who runs it but they do a good job. He’s happy to look at non-Renault’s too.
Another option, my old man swears by Crestwood Motors in Halesowen (uo by McD’s, near Tenterfields school, again, neither a diesel or VW specialist but he takes his diesel Passat there and rates them very highly.