Then you can get into the weeds about whether a leased line is dedicated or not because it's only 'yours' back to the exchange.
In any case this would fall under the remit of the ASA who were happy for FTTC to be sold as fibre, so I wouldn't be holding my breath for them to do anything.
BT could also argue that the fibre is dedicated to your internet connection, which is true, and that they made no claims over whether it was dedicated to your sole use. The wording is vague enough that I doubt any sort of complaint would go anywhere.
Edited by jpm (Mon 22-May-23 17:27:14)