I agree it is too off. I went on a search in Framburg and, interestingly, came up with two pendants, but with two different names…one is called Gala and the other Veronique.

These are from two different sites. They look identical, so you can have pendants that are similar, at least.

Wow, in the second picture they look like two different pendants. Lighting has a lot to do with it I'm sure, but these do not look like a matched pair.

These are pretty different. If the third one is going beside these two, AND if the 3rd one matches one of the two you already have, couldn't you get away with putting the one that does match the other two in between the matching ones.
Now, if the 3rd one is going over a different area, you could wait and see if the 3rd one matches either of these and if it does, use those two together. That leaves the one that is different to put over the sink or wherever you were going to put it.
These are only suggestions. I am not a decorator. I just identify because I just completed a kitchen remodel and selecting the pendant lights was one of the hardest parts. The hardest might be the pulls/knobs that I still do not have!

Variations in production occur whether you have handmade or manufactured products (which is why ALL the fabric purchased for a room, or the tile, should be some the same production run). That said, the difference in appearance in this case is too great--unless the third is so very different from the other two, yet in the same general design line, that it somehow "works". At the moment, it looks like a mistake.

My suggestion is to contact the company, plain that the variance is out of line but acknowledge that the third has not arrived and you're willing to see if the set pulls together when completed--adding that if not, you'll expect them to work with you to find an appropriate solution. Sadly, big firms often are driven by their systems and it can be challenging to address a specific case. But, good firms should have a way around the problem of people caught in the system. With luck, they'll respond positively right off the top. If not, ask to speak to someone with a "discretionary authority" to assist with special cases. Good luck!