Seeff Constantia not paying deposits back

I rented a house through SEEFF Southern Suburbs (Constantia Branch) and moved out over a month ago and have still not received the interest on my deposit which is due as per their contract within 7 days (no repairs were necessary). I thought due to lockdown that I would not get worried about it, but it is now well over a month and still nothing and below is their contract, they are now fully within breach of contract. The accounts department do not even reply (one person in particular)

3.7 On termination of the Agreement, the Deposit (or any balance thereof) and interest thereon, shall be refunded to the Tenant within 7 (seven) days after termination of the Agreement; or if repairs were effected to the Premises after termination, within 14 (fourteen) days thereafter.

This is a very scary situation, when a company that is supposed to be so trustworthy starts to behave in such a manner and starts withholding peoples money knowing that for the couple of thousand they owe, they will not get reported and attorneys will not get involved. The point though is that the money belongs to me and I am sure they are holding many other clients interest back, but because each amount is probably not significant, they probably gather no-one will do anything about it and they can just keep it. I lose more and more and more faith in these big companies as the days go by.