That's an interesting argument. You are suggesting that a utility supplier should investigate the bona fides of the person giving them authority to install in the property where they live.
How long would that take I wonder, and how much would it cost every applicant?
VM have been given permission, but clearly it was given by someone not authorised to do so. The non lawyer in me would suggest your remedy would be against the person who broke the terms of the lease.
But I trust that VM will avoid any legal case by removing the cable