Credit Card closed 2 years ago re-emerged, FNB Credit Card Department failed me.

I had a FNB classic credit card which I settled and closed in October 2018. On Monday, 11 May 2020 I received a notification that my credit is in a dormant status with a credit balance of R 300 that is due to me. I contacted the FNB credit card division verify the notification subsequently I was advised to send an email with my current banking details as I do not have any other active accounts with FNB. Query REF:***. On 24 May 2020 the funds were deposited into my bank account which to my understanding concluded my business with FNB. To my surprise I received a credit card statement with a required minimum payment of R 351.00 furthermore reflecting two over payments made to me on 21 and 22 May. Again on Friday, 19 June I received another R 300 payment from FNB. This morning, 03 July 2020 I received another R 300 deposit into my account, followed by a phone call from a rude credit card agent stating that my credit card that I closed 2 years ago is behind with more than R 900 What frustrates me is each time one these agents calls me I try to explain the situation and request for assistance with investigations in order to resolve the matter, in addition asked to be transferred to the manager or head of that department instead I was asked to send an email *** disputing the credit card statement which I did. All I received is an auto reply email with the reference number [REF:***] no one bothers to respond or try explain what is going on with the account. Can someone please investigate what is going on with this account in addition please ensure that you permanently close the account and ensure whatever errors that FNB is making on this account does not affect my credit profile.