Poor data capturing and greedy people

I have an account with Rochester home decor which was due to paid up in june 2021. I managed to pay the account before the due date for completion. On the 07 September 2020 i received a statement indicating that i owed R1371.00 which R1287.44 will be deducted on the 23rd September as per usual agreement. The deduction went through. The remaining amount was less than R80. On the 23rd October they deducted R1280.00 off my banking account which was a surprise since i know that i only owed them R80. I went to reverse the transaction.

Now I’m being harrassed with calls and sms’s claiming i owe them R1280.00. What irritates me is that i paid the account before the agreed term and i should have gotten reduction on my interest of the loan but instead,They did not reduce the interests and the loan amount remained as it was with interest after i have paid in advance.

I’ve asked them to check their statements but their call centre agents insists that i owe them R1280.00 and she said she can not check her statements. I’m very upset with their service.