The regular Paris phone number, plus the proper intl prefix minus the leading "0" as Michael explained, is the one you need to call.
It's for after sales inquiries ("Pour le suivi de commande"), which is clearly your case.

The 08xx number is for sales/reservations only - and cannot be reached from outside France anyway.

Generally speaking, toll-free numbers in one country cannot be called toll-free from other countries (the US and Canada, which share a country code, is one exception, but of course not all toll-free numbers in the US are toll-free from Canada, and vice versa).

And very often toll-free numbers in one's own country are not free when calling from a cell phone.

If you have a microphone (built-in or plug-in) you might consider calling from your computer using Skype. You can call internationally computer-to-phone for less than most international phone-to-phone per-minute rates. You have to download the software and add time to your account at their website www.skype.com. Call quality is usually very good. (Calling computer-to-computer is free, but that won't help you in this case.)

OK. I got an email from them.
It says:
__________________________________________________ ____________

Bonjour XXXXX jeanne

ACCUSE DE RECEPTION

--------------------------------------------------------------

Nous avons bien enregistré votre demande, numéro 604068-1319495376. Nous vous apporterons une réponse par email dans les plus brefs délais.

Si vous souhaitez nous re-contacter suite à votre demande, répondez
à cet email en conservant son numéro, [604068-1319495376],
dans l'objet de votre message de suivi.

Cordialement,
Le Service Client
L'équipe Billetterie

__________________________________________________ ________

My poor French suggests they're telling me they will respond after a brief delay. At least I now have an inquiry number.

THanks everyone. I will put this on hold until I hear back from them (or not). If I haven't heard from them before I leave then I'll just have to do it in Paris. Bah humbug.

Yes, that's right. They'll get back to you as soon as possible. And you have a reference number to use if you need to contact them again.

I realized the 2nd part of that email told me I could reply to it. I wrote back...hope I got this at least close to right!

I wrote: "Avez-vous quelqu'un que je peux correspondre à en anglais ? Merci beaucoup."

Hopefully, I'll have a resolution...in English...tomorrow morning. Fingers crossed.

Pretty good! Avez-vous quelqu'un avec qui je pourrait corresponder en anglais?

They'll have no problem understanding you. Good luck!

FNAC sent me a useless reply. In essense it says "we looked for your order, but could not find it". Duh. Neither could I! That was the problem!!!

However, the problem is resolved. The charges disappeared Tuesday night. They never really left the pending stage, but they stayed there for 3 days. Anyway, they're gone now.

I think I'll look for another way to buy museum tickets.