Cancelled car booking without notice, frustrating support channels, buggy integration with airlines

I booked flights and a car through Travelstart. On collection of the rental car, the Avis agent informed me that my car booking was cancelled by Travelstart. Travelstart didn't send me a notice of a cancellation, all I got was a confirmation letter that my rental car was booked with a confirmation number. Getting support from Travelstart was next to impossible. They do not publish a call centre service number. The only service channels are chat based via WhatsApp or their mobile app. I first tried WhatsApp. After some interaction with the chat bot, I was handed over to a human agent for whom I'm still waiting to respond. We tried the mobile app and there a human agent eventually answered via chat. The Travelstart agent's reply via chat was that our car booking was cancelled due to security reasons (even though the flight booking payment was fine) and that I will be refunded. No further assistance to get another car because of their mess up. So, we had to book our own car at the last minute at an additional cost of about R2000. On our flight back, the Kulula check-in agent said that we didn't book bags. So, we had to go and pay for it at their booking desk. When the lady there saw we booked through Travelstart, she said that there are issues with Travelstart and that we actually did pay for bags.