Charging me for something i dont know

We were a group workers and we got fired by a municipality and we approached LabourLawDex for help and their policies was if they win the case of returning us to work then we will pay them. They lost the case and to my suprise Labourlawdex has sent me an invoice of 15000 and when i try to call them their number is not going through. i am the only one who got that invoice and the rest of the group got nothing. I am not going pay something that i dont know off. They need to fix their error.