Thanks for your message Zach.
The outside work was completed today by Kier. I tried to call the pre-installation team but they told me they were still unable to get an engineer to install broadband until 21st Jan.
I had a 40 minute conversation with the same person (Gary in pre-installation) to try and get me transferred through to the customer care department but he refused to transfer me through, just kept telling me about the £30 compensation he was adding to the account (a downgrade on the £50 offered the other day). I said I didn't care about the compensation, it doesn't help me (as mentioned, I work from home and no access to internet is creating serious issues for me). I also asked for a recording of the phone call and made a Freedom of Information request - again, he kept deflecting and would not escalate my complaint or transfer me to another team. Eventually he hung up on me.
I have since made a complaint online but God knows how long that will take to respond to.
Now that the outside work has been done, I am hoping there other providers I can contact in order to try going with someone else. My Virgin Media contract ends in April or May anyway - given the issues I've faced then I'd like to think I can cancel early at no cost. Someone in this thread had already advised taking out a 30 day contract with someone else, so I'll be looking into that.
I'm amazed that VM don't provide customers with any kind of temporary solution when there are delays in getting internet installed (delays that are entirely VM's fault). I'm still paying for your services, yet you are doing nothing to help me.