Problems contacting Ameli to register

Hello,
I'm working in France as part of a research project. I'm in a International organisation so the paperwork is a bit different.

I'm having problems registering at my local CPAM. I think the process was started but I didn't leave the dossier at the office because I didn't understand the instructions well (my French is not good enough yet). Last week I contacted the English speaking line to ask about my case, and they told me they would ask my office to contact me via email to see how to continue the process.

The think is, I received a very kind call from my department's CPAM, and they said no problem to contact me via email to send the information and unlock the process. For my surprise, I was contacted from ne-pas-repondre.cpam-xxx@... I've tried to answer anyway, because I can't find an email anywhere else, and I've got an automatic answer saying that my email is going to be deleted. So, I'm back to a point where I can't contact them via email. Could someone from Ameli contact me via email privately so that I can send the information to somewhere I know is going to be received?

Thank you very much,