Phoneline and Broadband connection at rented home

[#1]

One of my friends has a house he has been renting out while he isn't living there, for the last 18 months. His newest tenant complained the phoneline wasn't ready for Broadband and BT were quoting £120 to reactivate the Phoneline and then he'd have to pay the activation fee for Broadband also. Too me this seems crazy as the previous 2 tenants have had phone and broadband working fine.
Trying to understand what has happened I'm guessing for some reason BT have disconnected the Phoneline and cancelled Broadband even though there was no instruction for them to do this.

What I need to find out for my mate is how he can avoid this happening again. Is there no way the Phoneline can be left connected and Broadband activation between tenants? Can't find any clear information on this...
Would this maybe mean my mate takes over paying for the Phoneline and Broadband instead of leaving it to his tenants? Not sure he'd be happy with taking responsibility for people's Internet usage or the tenant being happy about sharing what numbers they have called with their landlord.
Any ideas if this would cost anything while the house might be vacant?
Thanks for any help.

[#2]

unfortunately, I think that's how BT work it, if you cease a line, i.e. stop paying that's it, another £120 in BT's pocket

[#3]

i live in rented and didnt cost me the standard £120 to have a phone line but my sister moved into a appartment newly built had phone sockets in but as no one had previously had a phone line there she had to pay the £120 tto get connected at exchange.
so with people all ready having had a line at the address in my view they shouldnt be charging you to have a phone line.
at my house there hadnt bein a line in use for at least 2 years before i got connected but it could be somthing to do with the amount of space they have at the exchange maybe they disconnect lines at yours to create space.

[#4]

If you want to send me the address of the property, I'll be happy to check how much the charge should be.
If it's a stopped line, then it should just be £38.85, but it will be £105 if it is a new phone line provision.
Those are our prices anyway