I know for a fact that some
SEO companies are spamming the cr4p out of the Google LBC ... and its working for them.
There is one company in particular who have mastered the art of manipulating the listings/rankings for the Google LBC listings and it includes not only the Yellow Pages references. From their perspective, Google feed from not only Yellow Pages but many (some would say all) other directories on the web that contain information about your business.
One of their tactics is to go through any and all directory listings a business has on the web and ensure they all reference the same title and phone number and address. Sometimes this is possible.. other times not. As some directories rip their information from other directories and dont allow for updates etc.
From the extensive testing they have carried out this seems to be a key tactic that works when it comes to getting your business to rank in the business listings. So if you are having no luck with updating your listing by claiming it, or updating your Yellow Pages listing.. start looking further afield to other web directories such as True Local, Local Business Guide, Hot Frog, dLook etc.
The key seemed to be to ensure the phone number matches the address and the title of the listing. i.e dont have a listing for 'Dentist Orthodontist Sydney' with 1800 Dentist and Dentist Melbourne with 1900 Dentist. Go with different phone numbers for each of your listings.