I see no buttons that can be clicked to edit or update the address and
other contact information of a listed business. And Google does not
provide any help in this regard. I would appreciate it if any member
here can provide this missing help.

I don't like Google because they don't provide toll-free customer
service at all. Yahoo! is great and much more user-friendly.

Thanks!

Google provides plenty of help.  Click the Help link inside Google
Maps.  There you will find all the help you need, including how to
edit a listing.  Help > Local Business Center Help > Edit a Listing

You must claim the business.  Have you done this?  Are you following
the steps on the page Edit a Listing?

Yahoo provides toll free customer service for ALL of their services?

Think of this:  Google Maps is free.  They offer all business listings
for free.  Yet, customer service costs money and a toll free phone
numbers cost money.   Would you rather that everyone must pay to use
Google Maps?  I wouldn't.  So, the solution is obvious.

I have rarely seen a problem with Google Maps - and when one does
exist, Google has been very good about fixing it.  You can't ask for
anything better than that - ESPECIALLY for a free service!  Yes, I
have seen lots of people complain about problems.  But, 99.9999% of
them are caused by the end-user; you can't blame these on Google...

How robust do you think Google Maps would be if EVERYTHING must be
purchased - including each time you searched for a business location,
including each time you wanted a set of directions, including each
time you just wanted to find a street or city?  In your opinion, how
many people will pay?  Are you ready to pay for each use of Google
Maps, including the right to list your business?