2004 545i Automatic Transmission Failure

the 545i transmission started having problems during the 50K warranty period.  the dealer said the transmission was normal.  Many other owners have documented similar problems with this transmission.  At 60,000 miles there were more severe issues and the dealer told me it needs to be replaced. I was told by the dealer service rep that by documenting the problem during the warranty period, the warranty would be valid for a "reasonable" period after the warranty. BMW North America and the dealer are now saying they will not honor the warranty.  Do I have any recourse to motivate BMW to honor the warranty?