Experian SA "No Care"

I had a default with Experian which I successfully challenged and they removed it from my profile but however a month later this default was again re-instated , I am soo upset by this as I am in a process of purchasing a property. What further frustrates me they do not answer any form of correspondence , I have been calling them the entire week last but would hold for more than 30 min with no response. This is very frustrating to say the least , I feel like I am in their mercy and I must just wait they would attend to me whenever is suits them best. I am seriously annoyed by this and also feel a sense of helplessness.