They say they can't ban specialised numbers
Oh they can but since it is making them a ton of money why would they.
Here in the U.S.A. your provider can and will block area codes at your request.
In fact you can even buy a number blocker to hook up to your home phone. digitone.com
I don't know if this will help however I don't understand how your phone provider can FORCE you
to be responsible for something that you have no control over.
It's THEIR negligence, not yours.
To solve that problem here in the U.S. I would change my telephone provider while keeping my same phone number.
Also most telephone company customer service reps get evaluated on the amount of calls that they handle in a month.
They will blow you off with pat answers to get on to their next call.
That is why I ALWAYS ask for a supervisor, tell them that you are recording the call for better customer service and
then ask them for their first name and their company id. number.
You will be amazed how their manners to make you feel like a valued customer changes.
Stay persistant, write down times, dates, who you talked to, what they did to help you so you can prove in a court of
law that you did everything in your power to make a concerted effort to correct the problem.
This is your providers problem, not yours in which a honest court would find you not responsible for those tolls.
Once EVERYONE started doing this your provider would fix this money making scam for THEIR company.
Your telephone provider is VERY AWARE what is going on and it is making them a ton of revenue.
Good luck.