Jozi House Frame work refusing to pay my deposit back

I had stayed at Jozi house flats in Johannesburg for a few months, this was a join lease agreement I had in place.

I decided to then vacate the place a month later after the lady I signed the joint lease with passed away. I was then provided with papers to sign so that the my deposit can be paid out, I have signed everything needed and sent the forms back, it’s been months now and still I haven’t received my deposit back, I’m told to be the one to chase after the deceased kids for them to also sign the documents. Please bare in mind I have tried numerous times to get assistance from the management with no luck, all I’m getting from these people is that they called the deceased kids and there’s nothing more they can do so my deposit will stay will them even though I have signed the documents and the family of the deceased is not interested.