Disappointed customer of OK furniture store at Sebokeng plaza

I'm a customer with the shop I bought a Refrigerator in 2021 November I've been paying my instalment every month till January 2024 which was my last installment I paid R599 because I was told by 1 of the cashier in the store that I owe that amount On the 16th of January 2024 I received a call from OK head office telling me my account is in arrears of R159 I was surprised when I was told that my account is in arrears because early in January before I've paid my last installment the cashier in the store at Sebokeng plaza told me that I owe them only R599 which I made fully payment of it So now their Head office harassing me they tell me I have to pay R159 I don't understand why should I pay the amount because I went to the store to enquire about the last payment of which I was told to pay R599 which I did pay so now I'm so disappointed with the way their Head office been harassing me about paying R159