MBD lying about figures customers owe on their account

I have an account with Finchoice that was handed over to MBD I called them on the 27 July 2021 to ask for a discount and they said there isn't one available the lady confirmed I owe R4403.08 on my account I received a sms from MBD the same day that requires my ID number to open and it also had the same figure. I made payment as per the call and sms (letter) on the 27th, yesterday I called MBD to ask when I can get a paid up letter they said Friday today the 29th I called and they say I still owe R500 which was not on the system when I called nor the letter no manager is available I keep calling and no assistance from the consultants they are a bunch of ******.