3 ... Top National Australia Bank and No. Bad debt charges for Australia's top banks are expected to triple to more than A$7 billion ($5.6 billion) this year, as more borrowers struggle to repay loans and asset values fall as the economy slows. In most cases, banks usually close mortgage loans more quickly than a mortgage broker does. This is probably because a mortgage broker deals with two types of persons - the lender and the client. Resolving mortgage issues between these two is a time-consuming job.