Have you tried their chatbot? I have to admit that they're not my favourite way of making contact with businesses but my experience is that you can get your query referred to a real human being fairly quickly:
https://www.vodafone.co.uk/contact-us/?icmp=uk~1_consumer~topnav~3_help~3_help_and_support~4_chat_assistant&linkpos=topnav~1~3~3~4
Alternatively (if it's a mobile phone problem, rather than something like a broadband one), consider switching to Asda Mobile. You'll still b using Vodafone's network but at cheaper prices and with a UK-based support centre where they usually answer their phones very quickly:
https://mobile.asda.com/