Purchase of large blocks in South Africa I have thousand's of small-single, two and four blocks but sometimes need to build larger structures and thus, would like to know were in South Africa I can 
purchase these larger blocks without all the smaller blocks
There are some BrickLink stores that operate in South Africa. You should be able to get from them whatever you need. Here is the list of stores:  http://www.bricklink.com/browseStores.asp?countryID=ZA