Zzyss, I used to have the measly $1k credit limit, so I kicked up a stink on the phone to the CSR about how I was travelling overseas and I would be booking multi-week tours which cost more than $1k, so I needed the limit raised to $3k.
There was a problem with the fact that I had a history of late fees, however I think what I did was put the CSR said I could escalate the issue to a higher level where they would investigate and make a determination. I might have to put a letter in writing to Wizard but in a week I had my $3k limit.
I stopped having late fees and recently bumped it up to $3.5k online via the request form which has a max $500 limit at a time. I really don't need more than that, as I am very careful with my credit card, and now I have a NAB Gold Banking VISA debit anyway.