How to Stop Bt overcharging you for caller display if you use a line just for broadband, theyre website is horrible to navigate and find such stuff so here is the instructions

when logged into your BT account online

select myphone from the top

then select calling features from the left hand side

then select “change your calling features”

select the landline you want to change the calling features on
it should then show you the caller features you have in a list
in there you may well have an item like this selected >
“BT privacy at home + caller display” or something like that which is “marked” as being free ie they say it is £0.0 in cost (they dont show the hidden caveats)

if you dont receive calls at all or make them per month ie you just you use your landline for broadband then they will charge you £2.70 for not using it ?
below the above option is the an option that just says
“BT privacy at home” also for £0.0 this one will not expose you to the risk extra caller display charges.

Select this option instead and you should not be charged the £2.70 a month from now on, but that doesnt get you the £2.70 a month theyve been stealing from you as money for old rope.