I suppose it is an extra because they say it is. If they said that as part of the terms of sale of the service you bought, then that defined what you had bought and you decide whether you like that deal on offer or not.
I think that there is nowhere else to go with this.
If you are unhappy with them then you should go to a decent ethic ISP. That is how you stick it to them, by depriving them of revenue.
ISPReview will give you an idea of what users think. And you can ask here for recommendations. Plenty of people here will be able to give you a straight answer of whether their own ISPs are any good or not.
But if you stay with PusNet and keep giving them money then it means that you are sufficiently happy with them that you are not willing to make a move. Only you can know what you want to do about it. Right now you are just talking to the wall, because they have stopped listening to you. A well-organised ISP will migrate you in a few days with zero downtime.