As advised, I contacted the mobile number provided by text but have not received any response. At the moment, I do not know where I stand with respect to resolving the problem (which a forum team member suggested might require a new V6 box).
So, what's the next step? Do I just wait (forever) or do I pester the engineer at the other end of the mobile number by continually texting or even phoning? I have no idea how long I should be waiting for a response before I conclude that my issue is not in a queue/being dealt with.