Some problems relate to the maps themselves and some relate to the data that has been assembled by Google's crawl process and provided by data partners. My guess is that the maps team must be overwhelmed by the number of error reports, given the global scope of the content -- it can't all be right.
You should check whether this looks like a competitor hijacking a listing or a poor crawl that shows some unrelated content on your clients' Place Pages.
If the clients have claimed their listing and are submitting updates (and have verified by phone/card etc) then they don't have the form anymore. They should mention the problem in the appropriate Google Group. They should also check who is the data provider for your country and see if their data is still accurate, e.g. via another listing that they power.