PHP equivalent of .net AES encryption

Question

I am working on a data exchange integration with my client and the data they send me is encrypted using their C# encrypt method (below).

My app is running

Answer 1

It seems like the PHP Script is Using the wrong Mode:
https://msdn.microsoft.com/en-us/library/system.security.cryptography.symmetricalgorithm.mode%28v=vs.110%29.aspx
The C# Functions do not set any Mode so the default is CBC.
The PHP part uses ECB instead, which is not only wrong, but insecure.