I'm glad the seller will be sending you a new plant, most sellers will if you have only had it for a short time, Or if they don't have anymore of that particular plant then they will replace with something else you want or give a refund. There is actually a replacement policy that sellers agree to adhere to on the lily auction if they do not state their replacement/refund policy in the description or "about me" area.
I have only asked one seller (not on LA) for a replacement ( well I didn't actually ask for replacements I just asked what their policy was and they replaced them) of plants because they rotted, but that was because they got shipped when I wasn't expecting them and we had an unexpected freeze and they got mushy and rot set in and a few I could not save. I have one that is still fighting to make it and it will be a year in Dec; it looks like a small clump of grass and it's about 6-8" tall. That particular one would try and grow and then you could tell it would start to die back and then try and grow and then die back. I had been treating it in ground but finally dug it up and soaked it overnight in Banrot/Subdue Maxx solution then let it dry and then potted it up. I think it will make it but it may take awhile for it to get big enough to bloom. It wasn't a cheap daylily and I really wasn't expecting a replacement on that one especially since mine hadn't actually died yet and the seller had sold out and had a waiting list for that one but they sent one this fall and I am glad they did.
We have started soaking new arrivals in Banrot before we plant them here. I think with a plant being stressed from being dug and shipped it leaves it vulnerable and susceptible to things sometimes in our environment here and I want to give them a better chance at not getting sick. Also, if the plant already has rot when it was shipped it will help kill it and not cause any problems.
I hope yours makes it but if not at least you know you will be getting another one.