Great online journey, but a simple R4,000 refund has become a saga

Buying with WeBuyCars was a 5-star experience—the front-end stack/UI and overall process were excellent, and I did purchase a car successfully. My issue: I paid a R4,000 auction deposit on a car where I was the only bidder. I later asked to cancel because I’d found another (more expensive) car to buy with WeBuyCars. I was told to deduct the deposit from the final invoice, but I paid via the Ozow link (can’t change the amount) and was assured I’d be refunded. Weeks later, repeated WhatsApps, emails and calls—promises of escalations/call-backs—no refund. Collection experience also disappointed: I flew to JHB and the car was dirty inside and out, smelled of smoke, and had an empty tank. By comparison, a dealer via AutoTrader delivered another car to my house (also ex-JHB), spotless, full tank, with a small gift, and they owned the hiccups. What I want: Refund my R4,000 deposit and close the loop in writing.