Paid Up account

I do not know how this system works or who opened my two years ago account which was paid up.

Last month I received a call and I told the agent how is this account open if I paid it up and received a paid up letter?

I then emailed Chantel Vesser my paid up letter to correct this and today I am still getting a letter of demand? It is proven that this is how they exploit people to keep paying accounts which are closed. So disappointed in this financial service.