Statements or paid up letter

I was given a settlement amount in September 2018, and paid it via debit order over 3 months, as arranged. A couple of months later I get another call regarding the same account, but after explaining to the agent, she confirms that she'll send me a paid up letter, which I did not receive. It is now July, and another law firm has contacted re the same account, and MDB refuses to give a statement or paid up letter, they telling me to go to the store. What I want to know is why was my account returned to the store if it was still owing? And I never cancelled the debit order, why did they stop recovering from my account if I was still owing? And they also refusing to give me recordings of our conversations