Traditional banks do not typically lend to people with poorer credit. Of all the cases, your own bank is the best chance as they can see your full banking history and it they see good conduct (ie not going overdrawn, not missing payments) then they may lend to you. If your own bank doesn't then you will need to look to a non-bank lender.
WARNING: If you read this website, your chances of getting car finance with bad credit will dramatically improve.
Non-bank lenders are normally the experts in the field as if you have better credit, you would normally just get a loan from your bank. Therefore non-bank lenders are specialists in helping people with bad credit. They know all the right questions to ask you in order to give you the best opportunity of getting finance. And remember, they want to be loaning you the money. Its their business. They will work with you to understand your credit history, what happened that made you experience financial difficulty and as long as you are back on your feet and you can prove it, then you will be granted finance. All lenders have responsible lending conduct obligations, and must not enter into loan agreements if the loan is unsuitable for the customer.
All lenders and financial service providers must be a member of the Australian Financial Complaints Authority. Make sure you search for your provider on their website - Info about finding Financial Firm . If you cannot find your proposed lender on this website, do not use them, or if you have to, proceed with extreme caution.