Thanks. I'd say two things.
1. This "terms and conditions" page is not on, or linked to, the bdx futures page. I did not click through all the way to the end of the purchase process, of course, and it is possible that a link appears later in the purchase process, but the futures page has its own "how it works" page and these limitations aren't there.
2. There is a lot of language in what you posted about the right to limit or cancel "orders," but it seems to me that the OP is not about a canceled "order" but the non-delivery of a "purchase." That is, Total reserved the right to "reject any order you place with us, and/or to limit quantities on any order, without giving any reason," but they continue that "[y]our credit or debit card will normally not be charged if we reject an order, but we will process a refund if the charge has been made against your card." Here, they hit the card for the agreed 50% and kept it; at that point, it ceased to be an "order" subject to rejection.
Anyway, that would be my argument, both to Total and to a small claims judge, and yes, I most definitely would take this to small claims court. Because the wine is not unique, specific performance (delivery of the wine) is not likely to be an available remedy, but if you bought the wine elsewhere I think it very likely that they would be liable for the difference in price paid.
I hasten to add, I have done zero research w/r/t the law of any jurisdiction, am not offering legal, so much as linguistic, advice, and offer no expressed warranties and none are implied.