Any engineering mob in perth should be able to do it (not from perth don't know any sorry, you will have to call around) Looks like it was a home job, they will know what kind of metal to use (looks like it was just mild steel :S not good...) just take a bracket off (or get your mate to and send it to you) give it to said engineering mob and and just get them to make 2 triangular braces to strengthen the L shape plus use thicker steel, also look at getting high tensile bolts, they will be the next thing to snap.

Hope this helps?

Julz