Unkown debt (R 10 546.83)

In 2020 January I went to Sars (Rissik) just before the hard lock down. I went to do my returns of which I was advised that I am owing a thousand and some odds which I glady paid even though the consultant there couldn't explain what it was for. Four months down the line I received an sms that my Sars done my tax returns when I went to check on the Sars Mobi app. There I was owing Eight Thousand and some odds. I went back to Sars and the consultants in Rissik dodge my query that is not as yet the tax session she cannot assist, at the Bara branch they said this query is dealt with by the Rissik branch or the call centre. So I tried the call centre which I was advice to write an affidavit to dispute and I got feedback from the Head Office that this a branch query now I'm owing R 10 546.83. No consultant at Sars could help with This. I really need help and explanation as how this come to be, because on the tax returns that I have done now recently Sars is owing my 0.78. The intriguing part is that home screen is stating that the actual balance is R 21 129.66 however I need to pay R 10 564.83