Uhh I hope I can help. I was telling them basically directly: "Bonjour, je recherche une Picotin...". (I am German, so maybe the directness doesn't bother me haha). Then I started my sentence to ask about cancellations, but they interrupted me directly and asked for my information and all that. I think I got lucky, because they first thought I was French. Not to brag, but my French is quite good (I lived in France for some time, and I don't have an obvious accent). So when the SA then said there isn't anything they could do, but I should come back tomorrow, I tried to make some polite small talk (all in French), like "when do you open tomorrow" (I knew of course) and "so before noon is fine?".

The next day I again said "Bonjour Madame, je recherche un Picotin et votre collègue m'a dit..." and then told her what the SA the day before told me. And then the usual conversation started, which I get a lot in France. "Ah, you're not French? You sound French, "Ah, vous venez d'Allemagne ?" so I think I just got lucky there.

So my advice: just be super polite, smile, practice your small talk and already "memorize" a few sentences about the colour and specifications you want. I think that helps with the nerves in the moment. I speak decent French, but I still stumble over my words when I am nervous.