Account settled but still receiving statement showing payment

I am very upset with the incompetence of your accounts department. On the 22nd of December 2017 , I called your store to find out what my settlement amount is in order to settle my account. You sent me a settlement statement , which showed an amount of R2112.50 for account numbers 2 ********** 87-01 and 2 ********** 87-02 , and I then paid this amount on the 22nd December 2017. The transaction showed in your bank on the 27th of December, and you sent me a settlement letter on email correspondence between the 1st and the 5th of February 2018. As per me all was settled, until I received another statement showing an outstanding balance on the March 2018 statement. I am very disgusted with the **************** taking place here, and when I phoned your offices, I spoke to a very rude and unhelpful agent who refused to listen to me. Please will you set your records straight , as I do not owe you any more money , and you cannot charge me for insurance on an account which was settled in December already. This is very alarming , and I will not be dealing with you or any of your stores again.