Pay back the money Cell c

My wife's cell c account was put into arrears dua to her being put off in 2020 because of covid.we started paying the account to get it on track.anywho we kept on getting calls from a debt collector stating that the account is in arrears,and the wife kept on paying.so a few months back she calls accounts department to find out the balance to free the account,the consultant informs her that the account is already paid up and they need to refund us monies,a case was opened,case number given.No joy,from the time this inquiry was made,evertime the wife called in she was given a new case number and a new inquiry opened.its been a few months now,no refund or a letter to state that the account is closed in sight.not sure how Cell c is running such a big service provider but can't handle simple inquiries and solve simple client problems.Next step would be to pitch up at head office with a plack card stating"NO JOB NO FOOD PLEASE REFUND MY MONEY DUE TO ME". When it comes to Cell c wanting something from you,be it you taking a contact from them,then it is done very quickly,but let you need something done by them like to close a contact or anything else then you have a snowball's chance in hell.Cell c needs to up their game.