I made a non refundable booking by mistake.

On the 29th December I made a booking via [URL Removed] so I accidentally picked non refundable room instead of free cancellation room. After I noticed that I immediately notified [URL Removed] I again notified Sun international via email and the lady by the name of Caroline responded with an email that doesn't say anything. I responded three times and there was no response from her. I then called sun international head office and I spoke to the guy by name of Diron and he advised me that I can go to my booking and cancel but when I go there I can't cancel it and [URL Removed] at the same time is not helping. I want to go to the place at the same time I need to have flexibility to change date due to my work travel and my husband's availability. The reservation number is *** which I would love cancelled. I have made another booking which is flexible to show that I want to visit the place I was not playing on the website. The new reservation no. ***. I am dissapointed in the way that Caroline handled my case since I made it clear to her that is important that my booking be cancelled. Please assist, I understand there are terms, however mistakes to happen anyone can make one.