Garage refusing to pay for work they booked on car

[Guest]

Hi in jan I bought a convertible from my local garage..it became apparent almost immediately thst the roof was faulty and for the last 7 months it has been in and out of the garage and was still not sorted. The mechanic booked it into a vw garage and on friday they gave him a price which he agreed if I contributed.he now refusing saying he only wanted it diagnosed so he could do it ( 7 months so far and not fixed?) My car is now locked in a vw garage and I cant get it. Where do I stand I'm at my wits end with it

[des8]

On the face of it , and with the sparse details you have provided, you consider suing the dealer.
He booked it into the VW dealer so that is his fight not yours.
You either want the vehicle returned or possibly you reject it as unsatisfactory