I found Grants used to be ok, but now they will only talk to you if you have a new BMW.
Anything too old isnt where the money comes from anymore, so from a business point of view they dont seem interested.
I spent half hour there just waiting to talk to someone and then when I finally did, I was then asked to wait again because someone who had bought a car from them wanted to ask a question
Im sure they would do a good job, but customer service isnt their strong point.