I think 30% interest is too little.
The OP clearly has a problem with impulse control. More seriously, he has the grave moral failure of borrowing money from people, giving a written undertaking to pay it back, and then reneging on that promise.
His word cannot be trusted. His promises to pay his debts have been proven to be empty words.
Worst of all, he has the gall to blame his circumstances, not himself. The OP clearly doesn't have a basic clue about how life works, or how to assume responsibility for his own life. His parents might well bear some culpability for that.
What the OP fails to realise is that his previous unpaid debts (that caused his bad credit record) did not magically disappear, but were paid off by other people. Behind the simple accounting entry of writing off the bad debt lies the reality that the loss is recovered from the interest charged to other consumers. This the OP fails to see, or if he does, he seems to care not a fig. Debts don't just disappear, mate - they are paid by other people. Every Rand you get that you didn't work for came from someone who worked for it.
What he rather needs to do is save for 6 months or a year, buy an old jalopy like the rest of us did at some point, and live within his means.