Ithemba Properties Rental Deposit Complaint

I had paid R2500 for deposit prior to moving in at 260 Marshall in March 2020 and Ithemba Properties had a promotion running '1st month rent free'. When I received my deposit back on 15th of March 2021, I received R1300, 37. Up on calling to check what was going on, we (my guardian and I) whom had signed a lease for me were told "they took the discount back" and that if I had extended the lease for another 6 months I would have received my full deposit, **** about sending a letter to let me know of this which I never received. This does not make any sense at all,I am not happy about it. What kind of business takes a back a discount which themselves used to attract tenants, talk about bad business ethics.