P&G Faces Authenticity Complaint Over Head & Shoulders Conditioner Sold on Trendyol

I bought a Head & Shoulders hair conditioner, manufactured by P&G, through the seller "urban pantry" on Trendyol, and the product was delivered to me today. However, there's no expiration date on the back of the product, and the barcode number starts with 800. This raises serious doubts about whether the product is genuine.
To get this cleared up, I reached out to P&G. But instead of providing detailed information, I just got a dismissive response saying, "the products we ship are genuine." Yet as the company that markets these products in Turkey, they're the only ones who, based on their own records and production information, can give clear and definite information about whether the product I have is actually authentic.
For this reason, I'm requesting that the authenticity of the Head & Shoulders hair conditioner I purchased through Trendyol be verified, and that I be given a clear, written explanation that leaves no room for doubt.