Unfortunately Collection Agencies are paid hefty rewards to collect and whether they think their customer is in the right or wrong makes no difference to them. Their salary is based on their collections and they have blinders on when doing their job. I would rank them as low as telephone solicitors in annoyance.
We had a collection agency in the US call us repeatedly with even threatening and obnoxious voices to collect a charge 5 years prior that we were told by our insurance agency not to pay. Luckily I had this in writing and still had all the paperwork from that time and so I sent it to them which then they still proceeded to argue but in the end gave up since someone finally realized the customer's error.
This may not help you resolve your issue but maybe explain that these people are totally separate from the original collector of your money. If you have written proof that you were not to pay any $'s pending the litigation, then you need to repeatedly fax them these copies along with the understanding that this was a court ordered ruling and that even the penalties are not warranted and to leave you alone.
Life is not a child's game of follow the Leader. Instead, life is more about finding one's own purpose in life....your life's plan, and then making a positive difference on earth.