I also had the most appalling experience last year, when I called to discuss an issue with data usage. My call landed in India, then passed from pillar to post around different departments (all Indian), each one in turn blatantly fobbing me off in the hope that I'd give up. Online chat was even worse, a complete waste of time.
Worse than Demon, and I never thought I'd say that. I wonder if maybe the Demon call centre was thrown in when Vodafone took them over?
Such a shame as I've been with Vodafone about 15 years and until not long ago, customer service was UK based and always pretty good.