Having joined Virgin Media as a new customer on 8th April, I called ahead of time to set up broadband in time with the move into a new home. Both husband and I work from home. 2 days before the agreed installation date of 26th April I was told it's been extended to 24th May!! I have had several phone calls with Virgin media, all of which tell me something different. One even brought it forward to 7th May, only for the next day to be pushed back again to 25th May!! Going 6 weeks without internet is not acceptable VM!!!
Chances are there's a blockage somewhere preventing the cable installation and until that is resolved you are not going to obtain services regardless of how many times you ring up and the date you have been given is simply an estimate of when they think the work might be completed by and shouldn't be depended upon. A good rule of thumb is 8 weeks from the delay will give time for a planning permission to dig up any needed parts of the highway to fix the blockage and reschedule a cable pull. In the mean time you may want to investigate a cellular data plan to obtain internet whilst that is progressing.