Are you sure that's BB only? As I understand things, the fastest VM broadband offer of 1 Gbps is £62 a month if there's no discount, and the forthcoming price rise will add around 14% to that, making £71 depending on how VM calculate things.
You can of course leave or renegotiate if you've had notice of the planned price rise, but that opportunity exists only for 30 days after you get the notification. Also worth noting that VM are changing their terms so that next year you will be notified of a 4% + RPI increase but won't have any opportunity to leave or renegotiate if you are in a fixed term contract.
