Damaged Credit

I changed banks last year and tried to contact them, no answer, no call back. The collections department finally called me demanding payment.. I deposited payments using my ID number as reference as instructed; no payment was ever reflected and the company handed me over to an external debt collection agency. A year later, they still have not found my payments or returned my payments equaling over ten thousand. Please do not engage. I have researched how to fight back and there is no way; thousands of citizens have complained and nothing has changed.