My ex ISP was ZAZU. now they just charge a bit too high compared to others. But they had brilliant service. Anyways this is quoted from their FAQ site of how much 4Gigabytes really is and this is what i received from my 3GB package:
"The proper defintion of a Gigabyte according to international standards is one thousand million bytes (3 000 000 000). A Megabyte is one million bytes (1 000 000) and a kilobyte (1 000). However, in computer terms, it has become common to refer to a kilobyte as 1024 bytes, a Megabyte as 1024x1024 (1 048 576) bytes and a Gigabyte as 1024x1024*1024 (1 073 741 824) bytes. Telkom has chosen to use the latter definition for a GigaByte. Your 3 Gigabyte cap is therefore 3 221 225 472 bytes. (Thats over 200Megabytes more than 'proper' 3 Gigabytes). In fact, there is a proper name for the Gigabyte as we have defined it, and its called a 'Gibibyte' (also Mebibyte and kibibyte). However since virtually nobody uses this term, or have even heard of it, we stick to 'Gigabytes'. "
So i received 3221Mb each month from them which was a good thing.