payments reflects on their system but I have arrears

I got a statement to say my account is in arrears. on the statement the payments are reflecting but account shows arrears. I called into the call centre to enquire, spoke to Chris he said it will be fixed. then I received a call frm collections to ask when im making payment. I called again to the call centre to enquire I then spoke to Thulani who promised to call me back once he spoke to his superior but till now he hasn't. I still receive calls from collection s