On my most recent trip (two weeks ago) we had to postpone by 24 hrs (illness) and I can say that the JNB call centre were brilliant. We had expected to land up in just any old seats and as the PE cabin is small, we accepted that. However, we got ideal seats and the trip went well.
On the other hand, dealing with 'customer services' to get proof of the delay and payment made to make the insurance claim? Automated misery.