I took a loan with them for building material around 2019

I took a loan with them for building material around 2019. Then 2020 during covid 19 I could not make payment. For a period of 3 years I didn't hear from them. Until 2022 I received a call from a consultant when I raised prescription issue she informed me that an amount of R50 was paid by me which has disturbed prescription from running. I informed me that I have never made a deposit of R50 as my installment was around R1500.00. I have called and sent emails they said they will investigate to date I have never heard from them. I was made to sign a payment arrangement under false pretention that the debt has been decreased while it was a lie. Kindly assist.