Inconvenienced by suddenly cancelled flight

I booked a flight a week in advance from Mthatha to Johannesburg for 28 August. Flight number is 1448. I got a call from Mpumelelo from airport in Mthatha advising flight has been cancelled and I would be put on a flight leaving the following morning. I told him that was inconvenient for me as I have to catch another flight from Lanseria airport to Durban at 10am the following morning so I would prefer they put me an another flight same day or I would forfeit my other flight which Was paid for in advance. Mpumelelo then advised there’s nothing they could do accept for me to leave the following day.

Now this is extremely inconvenient because this has now meant I need to rebook my flight to Durban. I was not given much option as they should have rather given me option of leaving on an earlier flight same day. The customer care email address I was given *** bounces and there is no answer on their customer care lines ‭***‬/2355.