You mean 6 months into her 12 month contract?
£300 does seem a bit steep, maybe your sister would be better staying with BT for the six months, it will cost her less.
I suppose depending on what Broadband package she is on, but six months of option 3 is just over £146, so add in the BT vision and then the phone and it could be about righjt.
This is the problem with long contracts, you find a better deal, but you are stuck, unless you pay to get out.
Is your sister going to use Sky LLU broadband then
Adrian using Linux on his laptop and loves it.
BTBroadbandanywhere type package.