I recently went to the Cell C website to find out about their contracts. When I got to the home page I clicked on a "more" link which I thought would take me to the website content I was looking for, and to me it looked as though nothing had changed (even though the page had refreshed), as the same large flash advert at the top of the page kept playing - there was no indication that I had moved to the content that I had requested.
In my opinion, this is a serious usability issue - how do you expect people to find out more about your products if it appears to them that the link is not working. After trying again, I noticed that the flash advert at the top had a "button" labelled "check it". When you click on this it does takt you to the requested page, but it hardly looks like a clickable button, in fact, it looks like another graphic that's part of the flash advert.
I imagine that Cell C has a large web design/development budget. I would suggest that they use some of that to do some usability testing on their website with some average web users to find out how usable it is - I'm a web developer and spend all day on the computer and internet, and it took me a couple of goes to figure this out. Now imagine the average south african internet user. I'm sure that this would totally confuse them, and possible send them to a competitors site.