So, probably like many people I dont use my home phone and cant see the point of keeping it so want to get rid of it; why have I still got to pay the full price of the 'line rental' just to have the broadband? There are loads of people who dont have a land line now so why are we still being charged the full rate for line rental just so we can have broadband??
You get a discount for having the phone line. If you cancel it you lose the discount that can sometimes cost more not to have it.
AS VM have to run the cable to your home they would rather you have the line so they might make some money from calls. So they offer a discount for having the phone line with other services. Getting rid it it might cost more or the same. If more then keep it and never plug a phone into the line. If the same you can decide if to keep it or not