Using a sim only sim card the phone says no service
I have a sim only contract with Virgin. I broke my phone so put the sim in my old Vodafone iPhone. It said 'no service' so I got in touch with Vodafone and they said it needed unlocking, which they have now done. It still says 'no service'. I don't know what to do next and can't get in touch with Virgin as their webchat has the permanent message 'All of our agents are currently busy. Please try again later.' and obviously I can't call.
Does anyone know how to solve this, or how to get hold of Virgin on webchat?