Closing account nightmare

I recently paid my Game account up to date after I phoned them to get a settlement amount which the guy gave me. After that I asked them to close my account just to hear my account is R59 in credit could the guy who gave me the settlement amount not see that if I pay the amount he gave me it would have made my account in credit? Now it is such a mission to close the account, they asked me if they should write that amount off or pay it back to me there is no way you will write it off after I paid them thousands extra in interest, but now for me to get my money back I first have to write them a letter stating I want MY money back with my banking details copy of my ID and proof of payment? They are supposed to have all these details on their system as I paid via debit order? Surely they can see on their system I paid that amount and on which date, surely they have my ID on their system as I gave them a copy when I opened the account. Once again I will ask why are they so eager to give you credit but as soon as you want to close your account they make it such a mission? Why give a settlement amount if it will make your account in credit and then struggle for them to refund you