Account debited after contract have ended and has been cancelled

After canceling my debit order on 23 May 2020 telkom continued to debit my account in July, August September and October.

I tried going to a store to report and enquire about this only to be told there is nothing they can do and that they will log a call. After waiting for a representative to contact me I went back to the store multiple times since nobody was getting into contact with me . Helpless and frustrated I decided to reverse the debit orders

Finally a lady by the name of Gugulethu Mbatha got into contact with me regarding my quiry. According to her my record show that I canceled the account at the end of August and thus is liable for the month's as stated above. I then informed her that there was some kind of mistake since I have the confirmation of the account being canceled on 23 May and have a reference number as well.

She then asked that I email her the proof which I did. After forwarding the proof she stop replying to my emails. This happened almost 2 months ago and the bad thing is it has affected my credit score negatively. I was planning on buying a house this year but is not able to due to this.