Closure of account problems

I settled my account a month or 2 ago for my Truworths account, and suddenly I received a message saying I need to pay an Installment. I already paid the full credit amount I owed and now of a sudden I should pay an installment. And Truworths does not ask you if they can add more credit to your account, they just do it. I emailed them on the 9th of February 2021 to inform them I want to close my account because of this issue. I stil dis not receive feedback.