Frustrated with Travelstart's customer service, or lack thereof.

We have booked tickets with Travelstart for travel to Mykonos in June. There was a schedule change on Qatar's side whereby our JNB - DBN leg was cancelled and we were put on a BA flight at 09h30. This means we have a 6 hour layover in OR Tambo from a zero layover. I have been trying to change the flight to an earlier BA flight only to be told that Qatar does not have an interlink agreement with BA, and they cannot change the flight, which I know to be untrue. I contacted Qatar directly and they said it can be done but they cannot do it on their side. Travelstart has to do it. This is where the biggest problem comes in. You wait for an hour for a call to be answered, every email I send is responded to on days later, I have called and send multiple emails and I still do not have a resolution. We seem to be going around in square circles. My query is simple. Since COVID, this working at home nonsense, has made Customer Service non existent to these people. Your flights may be cheap, but your service is shocking and quite frankly not worth it. I have travelled many times with Travelstart, but this will be the last if I don't get this resolved before we leave. I need feedback, I cannot even find how to escalate this hence my trying this last resort on Hellopeter.