Jet stores won't close my account

I have on numerous occasions sent communication to Jet since 2020 to close my account and to date the account keeps accumulated balane owing due to their fees against the account. At first I settled these and advised them but instead of them closing the account, it is still active and accumulating more fees. Recently I received communication that they were going to hand me over if I do not pay the balance owing. I told them I had requested for account to be closed and they asked me for settlement letter. I cannot keep running around in circles with Jet. Please help.