Short-changed on rental deposit refund by goldburg Properties

I have rented property at unit 172 Bel-Aire Place Apartments Benoni, due to loss of income, I dully gave notice to vacate. My rent was R5200/month. Deposit was also paid. My deposit refund was R3034.24, this is after the extra EFT payment(in error) of R1900. There's no explanation as to why the amount is so low