Is your broadband less than 10Mbit ?

[Temp]

BT have a universal service obligation which could see them paying to upgrade it... but don't get too excited..

 

https://www.bt.com/broadband/USO

 

If the cost is less that £3500 they should pay. If more then you share the bill.

 

If you club together with neighbours it gets more complicated but that would be worth investigating.

 

 

[JohnMo]

They would only guarantee us 6.0mb

 

Went 4g can get between 12 and 40.  Had to buy modem at £100, then £35/m free mobile calls on landline phone and unlimited data