Although sympathetic to your issue , it’s a somewhat ridiculous argument to make , that BT , even though they are not your father’s provider, can have any control over the calls a Talk Talk customer can make , the more appropriate ‘question’ should be on a TT forum , or to TT directly, and that’s why can’t Talk Talk apparently ( with the appropriate checks and confirmations ) provide selected outgoing call baring….TT don’t resell BT telephony under their own label , TT telephony doesn’t involve BT , it’s their own ‘network’, any amendment or adjustment needs to be made by TT , no one else .
…so to your point , should your father or you ( who presumably jointed Talk Talk because of pricing ) who now find that the cheaper price actually comes with a cost , that being , call baring seems to be unavailable, should you / him join a provider that may cost more but offers more functionality, that’s a decision for you to make , but to suggest that currently the issue somehow involves BT is nonsense.
If your father was calling ( for example ) the ‘racing line ‘ ( that was operated by a third party that didn’t use BT in any way ) , to get the runners and riders for betting on horses , from their TT line , would the ‘racing line’ be responsible for him calling them ?
TBH , the very first reply gave the answer to your question.
