I have never had a bad experience dealing with VM CS. They are courteous and helpful. This is both at the Scottish call centre and overseas centre. If you're nice, pleasant and address them by their first name (they do like that!) they will bend over backwards to accommodate your needs and give you good deals.
I have no idea why other people are having bad experiences with them.
Believe it or not, VM CS is a big reason why I have stayed with them for the last seven or so years and won't be going anywhere else soon.