I've given Basingstoke the thumbs down previously Used to be fine years ago with honest guys working there, but went down hill with work not done as promised, parts not turning up, etc...
If you really must use a main dealer, I've had a good experience at Martins Winchester (buying and warranty work).
Chris`I has recommended VAG specialist SJB in Chineham, although bizarrely they wouldn't touch my dad's Golf when he inquired about solving an engine problem... "Don't have the special tools"