QUESTIONABLE REFUND POLICY

This company is the worst to deal with when it comes to refunding your deposit! They firstly advised that they had record of my banking details on their systems for the refund and it is the same account used which I paid my deposit from, then a week down the line they send me a form to complete to again confirm my bank details, then nothing further. Ive been calling their offices and emailing repetitively only to be told ' we have your banking details and we will let you know when we process your refund' This company is getting away with thousands of rands earned in interest on other people's money and they are not a financial accredited company- I actually need to know if this is even legal to hold people's money earn interest on it and just take as much time as they want to rightful return the funds??