How we can find trusted and professional locksmith and security businesses in Melbourne?

ask local small business owners -- they likely have experiences with local locksmiths

You search "locksmith Melbourne"  I'd say bout all are trustworthy an professional.  Not sure which Melbourne your in. But i know in the states most places you have to get a special license to do locksmith work.  So there usually professional an safe.  That doesn't mean they won't be a grumpy old man.