Basic-Fit complaint: Vaccine card refused

I have held a membership at the chain location in Echirolles, France. However, though I have been attending regularly for over two months, I am now being singled out and refused entry because of my American vaccine card. Claire, the manager of the three gym locations in Echirolles, has repeatedly singled me out and harassed me when I have attended gym but has now gone further and refused me entry. She has banned me from all three locations in Echirolles because she refuses to accept my vaccination card. I attempted to make a complaint locally but was unable to speak with anyone besides this woman Claire. She would not give me any contact information for someone else to speak to. I fail to understand why after attending for months, my vaccination card is no longer acceptable. I also fail to understand why, if this vaccination card is enough for the French government to allow me entry into the country, it is not enough for me attend this gym. I am not sure if it racism or xenophobia, but I am extremely upset and angered by her behavior. I would appreciate the company assisting me with this issue but I will seek out legal help if I must.