Paying them £100, for something they have refused in the past, seems like a rather optimistic waste of money.
The building owners will be seeking to avoid unnecessary damage to the building or grounds. Some of the worst examples of VM's installation work which pop up in photos on here are truly terrible so the building owners may be seeking to avoid this possibility happening.
Also, granting a right of access to install a cable to the property is also likely to involve future legal rights of access for VM for maintenance purposes which again the building owners will probably be seeking to avoid.
Plenty to potentially benefit the leaseholders from installing a VM cable, probably not so much for the freeholders of the building.
As for whether you have any legal 'right' of access to install new services, you'd probably have to seek legal advice on that.