I would contact customer service or wait for a mod they can see the reason for the tech no show. There would have been 3 texts out 1 to confirm the appointment, another day before and one on the day.
£26.24 for a no-show without 24 hours prior notice and £5.25 per day if VM fails to activate the services by 11.59pm on the date initially confirmed in writing with the customer.
and OFCOM (but rates not up to date in the link below)
Does your mother already have a VM cable coming from the VM cabinet in the street to her property?
I'm not sure at all
VM should have a record of a past installation but not of its current status. You'll need to get back onto VM to find out why the tech did not appear. Also start keeping good records and comm's of all dealings with VM inc. dates and times of promised visits, no-shows etc. so you have a good record if you need to argue with VM in the future ref any compo due.