Kindle ebooks have no ISBN. They only have Amazon's own Product identifier: ASIN which needs not be associated to an ISBN.

If he gave the excerpt the same ISBN, then it's really his own fault:

An ISBN is assigned to each edition and variation (except reprintings) of a book.

http://en.wikipedia.org/wiki/International_Standard_Book_Num...

Sure, Amazons customer service could be better and should probably at least have sent an email stating that they're lowering the price etc.