Unprofessional!

I'm not happy with this MBD debt collector. I agreed to pay my Std credit via debit order with them when they called me and I kept the agreement none of the debits bounced. Then Nov 2022 I sent an email to the lady who was helping me with this whole process, her name is Charity Nthlamu. I requested her to send me an updated statement so I could check my outstanding balance. And she sent the statement dated 26 Nov 2022 and my balance was R229.13. Then in December 2022 a debit of R246 went through on my account. I sent Charity an email in Jan 2023 asking for a settlement letter because as far as I knew I was done with paying the Std credit card. She didn't respond to my email, I called the number I found on the statement and spoke to someone else who was going to check and come back to me but they didn't. The next thing end of Jan 2023 a debit of R246 went through again, I reversed it. And after that I've been getting so many calls about the amount that they say is still outstanding. I keep explaining why I'm not paying because from the statement there has been a discount adjustment so what I owed is fully paid. I forwarded them the statement nobody gets back to respond about that statement. Instead I keep getting calls and feel like I'm now being harassed. I got a statement from them but now I'm told I must still continue to pay. No! I feel that they are very unprofessional, how can there be incorrect information in their system and now I'm expected to pay for whatever their mistake is. I'm very unhappy about their unprofessional manner.