The first and foremost question is: Is there any warranty left on the vehicle? If so, take it to the dealer and let them fix it.
Other than that, you will need to take it somewhere (preferably not AAMCO) and have them connect a transmission scan tool to it to find out what is wrong. These transmissions are electronic and have fairly advanced diagnostics built in. The checking with a scan tool, interpreted by a competent transmission mechanic, will likely tell the whole story.