DHL SA *********** and uncaring

I have have an ongoing problem with a suitcase sent from Australia to Johannesburg in March 2020. Due to Covid-19 and international borders being closed, DHL was requested to return the suitcase to Australia. After more than 30 emails and dozens of phone calls, the situation remains unresolved. I appreciate that DHL staff and working times have also been affected, but there is simply NO coordination between departments or even different people I've spoken to. I've been given conflicting information all along and they simply DO NOT follow up, or they come back requesting the same documents over again. In spite of my best efforts to avoid this, the suitcase was sent to the State Stores and they require payment of R5000.00 plus R10.00 per day storage! This, because of their own ineptitude and incompetence. My niece has accepted a quotation from DHL in Australia, for the cost of returning the suitcase, but was told that SA customs was refusing to release it. I have followed up several times since then and find I'm just going around in circles. Two weeks ago, I asked to speak to someone senior who was, of course, not available. I took the precaution of asking for her direct number. She didn't return my call, as I suspected would happen and, when I tried the number a week later, I received a "call ended" response (several times)! I've sent a complaint on their website and also had no response. Where to now????