I don't think a C18 with gold hardware is difficult to get. At my home store I want a C24 yet they seem to have a higher volume of C18's mainly because the demand for smaller bags is still high. If you are set on a colour and hardware then don't settle. There are times when I am specific and times when I'm open minded with Hermes. I have purchased things that were off from my wishlist and have been happy, and other times when I have not been happy....luckily more often than not I have been extremely happy. Etoupe with white stitching looks great with PHW. I have a Gold togo Kelly with PHW and I prefer it because of the white stitching, whereas I see an overwhelming preference to gold/GHW on the H forum. I always think I want GHW, and then when I get PHW I am so happy I did - it's an understated look and I can get away with it in the daytime without looking over the top- I happen to live in a very casual city so I like to just blend into the crowd and I don't like attention drawn on me.
I don't own anything that is Tadelakt leather but I do own Chanel lambskin. If you baby your Chanel lambskin, then you will feel ovewhelmed with the scratches on any smooth leather. However, keep in mind that when Epsom scratches, it can't be rubbed out. It's just a superficial scratch on embossed leather. The Tadelakt can be repaired more easily. This is a bonus for Tadelakt in my opinion.
Don't worry about not being offered another bag, you will get another bag. I think you should likely walk away from this one and consider it a learning experience. Your dream C will come along sooner than you think