OMG Lizl, i can relate. i too am in SA and have had a similar experience where i was told to give my cat way too much insulin and if it weren't for the angels on this board he would have died. He CERTAINLY would not be OTJ (Off the Juice) today and be doing as well as he is.
I don't know why the vets can't do just LITTLE research and ensure they are giving the correct advice to owners of FD cats

It is heartbreaking to think of all the cats who are dying and suffering unnecessarily.
What I learned here which will help you too :
1. try a diet change (low to no carbs - i.e. raw food homemade diet) first UNLESS kitty's BG #'s are too high for too long and he is looking dodgy. Often a diet change can work miracles if the FD is caught quickly enough.
2. Start with 0.05U insulin. The one which i asked for was LANTUS. It is the best available in SA, and one can purchase it in little pens which is far more economical because hopefully your kitty will get OTJ and you won't need it for long. Hopefully.
3. NEVER shoot without taking BG first. NEVER EVER.
4. Ask for advice here, no matter how trivial the question may seem. The people here are incredibly knowledgeable and my cat (and my other kitty) owe their lives to them. Errol because he is now OTJ and 2nd kitty because I now know what to do to try and prevent FD.
I've PM'd you my email and phone number and if i can help in any way please let me know. Sending your kitty lots of cuddles. Be strong, you can beat this.
BTW, when you have a chance, make a spreadsheet for Hansie so that the folks here can give you the best advice. It's imperative to know how his BG is looking at just a glance. It also gives you a place to make notes so that you have all the necessary info easily on hand.